Add the ability to provide a configuration file on CLI launch

[alallema]

Description
Currently, the firebase extension allows via a script to import the existing documents already present in Firestore before its installation.
To do it, the script proposes two ways to be launched in prompt mode and in command-line mode. It will be nice to add the possibility to launch the script with a configuration file that would contain all variables.

Basic example
File with configuration fields:

LOCATION=us-central1
COLLECTION_PATH=movies
FIELDS_TO_INDEX=
SEARCHABLE_FIELDS=
MEILISEARCH_INDEX_NAME=movies
MEILISEARCH_HOST='http://138.68.183.199'
MEILISEARCH_API_KEY='masterKey'

Command line to launch the script:

npx firestore-meilisearch -f <path_to_file>

npx firestore-meilisearch --file <path_to_file>