Add support for multiple Databases for firestore native mode

[hemanshv]

add code to support configuration of multiple Db in firestore native mode

[jskeet]

Please could you change the first line of the commit to "feat: add support for multiple databases" or similar? That way it will be picked up in release notes. (Just run git commit --amend to amend the commit, then git push -f to push it.)

[hemanshv]

sure Jon

[hemanshv]

@jskeet please review but do not merge, Expecting an integration test will fail because the feature is not launched yet.

[hemanshv]

Thanks Jon for the review will address the review comments.

[jskeet]

Merge branch 'googleapis:main' into firestoreMulitpleDB

Rather than merging main into the feature branch, it's better to pull main, then rebase the feature branch onto it. We can go over this in the retrospective later.

[hemanshv]

yes Jon Sure

[hemanshv]

@jskeet I have addressed the review comments, Please review. Thanks,

[hemanshv]

@jskeet fix the nits please review Thanks,

[hemanshv]

@jskeet I have addressed the review comments. Please have a look and provide your feedback.

[jskeet]

Right, will look when I get a chance (will be after our meeting).

[hemanshv]

Right @jskeet we cannot merge it as the feature is'nt GA yet.

[jskeet]

Importantly, the diff now shows that there are no API changes :)