Changes to enable communication with JVerify

[keyboardDrummer]

Depends on strata-org#292

Changes

1. Move Laurel grammar from a .lean into a .st file, so it can be consumed by the javaGen command
2. Do not let the Laurel grammar use fn or type, since those are not needed and are not supported by javaGen
3. For source code positions, store byte code array offsets in the AST nodes, so that when parsing programs from Ion, these can be filled in without having access to original source files
4. Enable the Ion deserialization code to deserialize multiple files where each file has a filepath and a program AST.
5. Add a laurelAnalyze command to StrataMain that for now will serve as a root for Laurel related interactions. I can imagine that in the future we will introduce an analyze command that is agnostic to the dialect used.

Testing

• Laurel pipeline changes (1-3) are covered by existing tests
• (4) Added a test for the newly introduced Ion.fromIonFiles
• (5) No test added, although I've successfully used this command from https://github.com/aws/jverify/pull/372