Also eliminate most usages of `FSTDocumentKey`, remove most methods from the Objective-C class and make it just a wrapper over `DocumentKey`. The only usage that cannot be directly replaced by C++ `DocumentKey` is in `FSTFieldValue`.
* Drop acknowledged mutations in schema migration (#1818)
Drop acknowledged mutations in schema migration as part of removing held write acks.
Port of firebase/firebase-js-sdk#1149
* Change removeMutationBatch to remove a single batch (#1955)
* Update Firestore Generated Protos
* Adding UnknownDocument and hasCommittedMutations (#1971)
* Removing held write batch handling from LocalStore (#1997)
* View changes for held write acks (#2004)
* Held Write Acks Unit Test Fixes (#2008)
* Held Write Ack Removal Spec Tests (#2018)
* Fix integration test
* Define a Comparator for DocumentKey
* Automated migration from FSTDocumentKeySet to DocumentKeySet
* Manual fixups for DocumentKeySet
* Delete FSTDocumentKeySet
* remove conversions in `Local` and `Remote`
* replace `FSTSnapshotVersion` in `Model`
* replace `FSTSnapshotVersion` in the rest
* let test check equal with C++ equal
* fix newly added code
* address changes
* Filter out document updates from target association changes
* Move remote-event-modifying methods onto remote event
* Style
* keep limbo docs in remote event
* Implement identification of limbo document updates
* Refactor a bit to handle removes as well
* Drop newline
* Handle synthesized limbo deletes
* Response to feedback
* Appease the style gods
* naively remove FSTPath import and source/test files.
* port FieldPath, part I
* port FieldPath, part II
* port ResourcePath, part I
* port ResourcePath, part II
* the grand commit to fix build errors
* use testutil:: helper instead of those from FSTHelpers
* fix test and lint
* use c_str in errmsg directly
* fix
* fix
* make code clean
* fix integration test I missed
* fix to avoid naming collision in preprocessor
* address changes
* address changes
* address changes
* fix: fieldMask are actually shared with different context.
* address changes
* add converter function between two DocumentKey implementations
* add unit test
* address changes
* fix lint
* using DocumentKey in model except for the container types `FSTDocumentDictionary`, `FSTDocumentKeySet`, and `FSTDocumentVersionDictionary`
* change other place w.r.t. the use of `DocumentKey` in model
* update parameter of test helpers from NSString to string_view
* revert a temporary change used in debug
* address changes
* Move all Firestore files to Objective-C++
* Update project file references
* Don't use module imports from Objective-C++
* Use extern "C" for C-accessible globals
* Work around more stringent type checking in Objective-C++
* NSMutableDictionary ivars aren't implicitly casted to NSDictionary
* FSTMaybeDocument callback can't be passed a function that accepts
FSTDocument
* NSComparisonResult can't be multiplied by -1 without casting
* Add a #include <inttypes.h> where needed
* Avoid using C++ keywords as variables
* Remove #if __cplusplus guards
Konstantin Varlamov