build(bazel): pin bazel version to 7.0.0 (#2360)

Pin the Bazel version used and executed by Bazelisk to guarantee that
TFLM is built with a specified version of Bazel.

When the latest release of Bazel went from version 6.3 to 7.0, our
builds, which were set to follow the latest release (because there was
no .bazelversion), were disrupted due to incompatibilities. By pinning
the Bazel version, we prevent such surprises in the future.

Revise the developer documentation to mandate the use of Bazelisk.

According to [Bazelisk documentation](https://github.com/bazelbuild/bazelisk/blob/9d3fc7d5e356071d2d40b75e69694a0c124e5e33/README.md#ensuring-that-your-developers-use-bazelisk-rather-than-bazel),
direct installations of bazel typically use a wrapper script which
checks .bazelversion also.

BUG=see description

Author: rkuester

.bazelversion

@@ -0,0 +1 @@
+7.0.0

CONTRIBUTING.md

@@ -4,25 +4,27 @@ https://github.com/ekalinin/github-markdown-toc#auto-insert-and-update-toc
 -->
 
 <!--ts-->
-   * [How to Contribute](#how-to-contribute)
-      * [Contributor License Agreement](#contributor-license-agreement)
-      * [Community Guidelines](#community-guidelines)
-   * [Code Contribution Guidelines](#code-contribution-guidelines)
-      * [General Pull Request Guidelines](#general-pull-request-guidelines)
-      * [Guidelines for Specific Contribution Categories](#guidelines-for-specific-contribution-categories)
-         * [Bug Fixes](#bug-fixes)
-         * [Reference Kernel Implementations](#reference-kernel-implementations)
-         * [Optimized Kernel Implementations](#optimized-kernel-implementations)
-         * [New Target / Platform / IDE / Examples](#new-target--platform--ide--examples)
-   * [Development Workflow Notes](#development-workflow-notes)
-      * [Initial Setup](#initial-setup)
-      * [Before submitting your PR](#before-submitting-your-pr)
-      * [During the PR review](#during-the-pr-review)
-      * [Reviewer notes](#reviewer-notes)
-      * [Python notes](#python-notes)
-   * [Continuous Integration System](#continuous-integration-system)
-
-<!-- Added by: advaitjain, at: Thu 16 Sep 2021 11:43:42 AM PDT -->
+* [How to Contribute](#how-to-contribute)
+   * [Contributor License Agreement](#contributor-license-agreement)
+   * [Community Guidelines](#community-guidelines)
+* [Code Contribution Guidelines](#code-contribution-guidelines)
+   * [General Pull Request Guidelines](#general-pull-request-guidelines)
+   * [Guidelines for Specific Contribution Categories](#guidelines-for-specific-contribution-categories)
+      * [Bug Fixes](#bug-fixes)
+      * [Reference Kernel Implementations](#reference-kernel-implementations)
+      * [Optimized Kernel Implementations](#optimized-kernel-implementations)
+      * [New Target / Platform / IDE / Examples](#new-target--platform--ide--examples)
+* [Development Environment](#development-environment)
+   * [Prerequisites](#prerequisites)
+   * [Recommendations](#recommendations)
+* [Development Workflow Notes](#development-workflow-notes)
+   * [Before submitting your PR](#before-submitting-your-pr)
+   * [During the PR review](#during-the-pr-review)
+   * [Reviewer notes](#reviewer-notes)
+   * [Python notes](#python-notes)
+* [Continuous Integration System](#continuous-integration-system)
+
+<!-- Added by: rkuester, at: Fri Dec 15 04:25:41 PM CST 2023 -->
 
 <!--te-->
 
@@ -143,10 +145,20 @@ Please see the [optimized kernel implementations guide](tensorflow/lite/micro/do
 Please see the [new platform support guide](tensorflow/lite/micro/docs/new_platform_support.md)
 for documentation on how to add TFLM support for your particular platform.
 
+# Development Environment
 
-# Development Workflow Notes
+We support amd64-architecture development and testing on Ubuntu 22.04, although
+other OSes may work.
+
+## Prerequisites
+
+TFLM's primary build system is [Bazel](https://bazel.build). Add
+[Bazelisk](https://github.com/bazelbuild/bazelisk) as the `bazel` executable in
+your PATH ([e.g., copy it to `/usr/local/bin/bazel`](ci/install_bazelisk.sh)) to
+automatically download and run the correct Bazel version as specified in
+`//.bazelversion`.
 
-## Initial Setup
+## Recommendations
 
 Below are some tips that might be useful and improve the development experience.
 
@@ -156,7 +168,9 @@ Below are some tips that might be useful and improve the development experience.
 * Code search the [TfLite Micro codebase](https://sourcegraph.com/github.com/tensorflow/tflite-micro@main)
   on Sourcegraph. And optionally install the [plugin that enables GitHub integration](https://docs.sourcegraph.com/integration/github#github-integration-with-sourcegraph).
 
-* Install [bazel](ci/install_bazelisk.sh) and [buildifier](ci/install_buildifier.sh).
+* Install
+  [Buildifier](https://github.com/bazelbuild/buildtools/blob/master/buildifier/README.md)
+  ([e.g.](ci/install_buildifier.sh)) to format Bazel BUILD and .bzl files.
 
 * Install the latest clang and clang-format. For example, [here](ci/Dockerfile.micro)
   is the what we do for the TFLM continuous integration Docker container.
@@ -184,6 +198,8 @@ Below are some tips that might be useful and improve the development experience.
   cp tensorflow/lite/micro/tools/dev_setup/pre-push.tflm .git/hooks/pre-push
   ```
 
+# Development Workflow Notes
+
 ## Before submitting your PR
 
 1.  Run in-place clang-format on all the files that are modified in your git