Saving Date.distantPast to Firestore leads to crash

* Xcode version: 13.4.1
* Firebase SDK version: 8.10.0
* Installation method: `CocoaPods `
* Firebase Component: Firestore
* Target platform(s): `iOS`

When I try to save to Firestore a date object that is `Date.distantPast`, I get the following crash:

```
*** Terminating app due to uncaught exception 'Invalid timestamp', reason: 'Timestamp seconds out of range: -62135769600'
*** First throw call stack:
(
0 CoreFoundation 0x00007fff20405604 __exceptionPreprocess + 242
1 libobjc.A.dylib 0x00007fff201a4a45 objc_exception_throw + 48
2 CoreFoundation 0x00007fff204054e2 -[NSException initWithCoder:] + 0
3 FirebaseFirestore 0x000000010dba641d -[FIRTimestamp initWithSeconds:nanoseconds:] + 269
4 FirebaseFirestore 0x000000010dba6219 +[FIRTimestamp timestampWithDate:] + 201
5 FirebaseFirestore 0x000000010da5bf07 _ZN8firebase9firestore3api13MakeTimestampEP6NSDate + 55
6 FirebaseFirestore 0x000000010dbb6bc0 -[FSTUserDataReader parseScalarValue:context:] + 1616
7 FirebaseFirestore 0x000000010dbb43eb -[FSTUserDataReader parseData:context:] + 1275
8 FirebaseFirestore 0x000000010dbb4d4e __45-[FSTUserDataReader parseDictionary:context:]_block_invoke.65 + 254
9 libswiftCore.dylib 0x00007fff30c50631 $ss26_SwiftDeferredNSDictionaryC23enumerateKeysAndObjects7options5usingySi_ys9UnmanagedVyyXlG_AHSpys5UInt8VGtXBtFTf4dnn_n + 321
10 libswiftCore.dylib 0x00007fff30a316c5 $ss26_SwiftDeferredNSDictionaryC23enumerateKeysAndObjects7options5usingySi_ys9UnmanagedVyyXlG_AHSpys5UInt8VGtXBtFTo + 37
11 FirebaseFirestore 0x000000010dbb495b -[FSTUserDataReader parseDictionary:context:] + 1067
12 FirebaseFirestore 0x000000010dbb4079 -[FSTUserDataReader parseData:context:] + 393
13 FirebaseFirestore 0x000000010dbb25d5 -[FSTUserDataReader parsedMergeData:fieldMask:] + 405
14 FirebaseFirestore 0x000000010dafb5d3 -[FIRDocumentReference setData:merge:completion:] + 323
15 FirebaseFirestore 0x000000010dafb2c9 -[FIRDocumentReference setData:merge:] + 89
```

Looks like a bug, but if that's an intended behavior, is there a convenient way to check if a date object is ok for Firestore (or to convert it to the nearest valid one)?