fix(firestore): Export Filter type from Firestore

[danReynolds]

Filter from Firestore isn't exposed on the exports. It'd be helpful to add I think so that folks can use it directly from this package.

Resolves: #2191

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[lahirumaramba]

Thank you @danReynolds for the contribution!
We need to update the api docs. Please do npm run api-extractor:local and push the new changes.

Please also update the unit and integration tests. For example:

firebase-admin-node/test/integration/firestore.spec.ts

Line 114 in 1342b45

expect(typeof admin.firestore.GeoPoint).to.be.not.undefined;

[jhuleatt]

I added a test and ran API extractor in #2192, so I think we can use that one instead. I set @danReynolds as co-author

[jhuleatt]

#2192 has been merged! Thanks for starting this work, @danReynolds!