fix(server): Support google.protobuf.Timestamp values for the storage write API

[coxley]

Summary

While BigQuery recommends to send TIMESTAMP columns encoded as int64, they also support google.protobuf.Timestamp: https://cloud.google.com/bigquery/docs/supported-data-types. This is critical for workloads that ingest JSON data, where RFC3339 strings can naturally decode into a timestamppb.Timestamp.

The client SDK making this easier with the following issue and PR:

• bigquery/storage/managedwriter/adapt: Schema to protobuf descriptors weird for TIMESTAMP columns googleapis/google-cloud-go#12569
• feat(bigquery/storage/managedwriter): allow overriding proto conversion mapping  googleapis/google-cloud-go#12579

Testing these changes work against Google, but panic the emulator:

panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x2 addr=0x60 pc=0x10387d398]

goroutine 8764 [running]:
github.com/goccy/bigquery-emulator/types.normalizeData({0x10541b980?, 0x14002391318?}, 0x0)
        /Users/coxley/projects/fork-bigquery-emulator/types/types.go:547 +0x88
github.com/goccy/bigquery-emulator/types.normalizeData({0x105529660?, 0x1400264d080?}, 0x140026da1e0)
        /Users/coxley/projects/fork-bigquery-emulator/types/types.go:575 +0x394
github.com/goccy/bigquery-emulator/types.NewTableWithSchema(0x14002330248, {0x14001471238, 0x1, 0x103a9316c?})
        /Users/coxley/projects/fork-bigquery-emulator/types/types.go:479 +0x398
github.com/goccy/bigquery-emulator/server.(*storageWriteServer).insertTableData(0x140025dcba0, {0x105869c28, 0x1400264d0b0}, 0x1400220c3d8, 0x1400083c150, {0x14001471238?, 0x4?, 0x10544dca0?})
        /Users/coxley/projects/fork-bigquery-emulator/server/storage_handler.go:691 +0x44
github.com/goccy/bigquery-emulator/server.(*storageWriteServer).appendRows(0x140025dcba0, 0x1400083c2a0, {0x10588ca80, 0x14001612000}, {0x1058750d0, 0x14002430980})
        /Users/coxley/projects/fork-bigquery-emulator/server/storage_handler.go:515 +0x428
github.com/goccy/bigquery-emulator/server.(*storageWriteServer).AppendRows(0x140025dcba0, {0x1058750d0, 0x14002430980})
        /Users/coxley/projects/fork-bigquery-emulator/server/storage_handler.go:437 +0xb0
cloud.google.com/go/bigquery/storage/apiv1/storagepb._BigQueryWrite_AppendRows_Handler({0x105720fa0?, 0x140025dcba0}, {0x105870a20, 0x140026da3c0})
        /Users/coxley/.go/pkg/mod/cloud.google.com/go/bigquery@v1.60.0/storage/apiv1/storagepb/storage.pb.go:3365 +0xdc
google.golang.org/grpc.(*Server).processStreamingRPC(0x140015d5000, {0x105869c28, 0x1400264cbd0}, {0x10587b040, 0x14000652d00}, 0x1400263e6c0, 0x140025dcc60, 0x106c72ac0, 0x0)
        /Users/coxley/.go/pkg/mod/google.golang.org/grpc@v1.62.1/server.go:1680 +0xe54
google.golang.org/grpc.(*Server).handleStream(0x140015d5000, {0x10587b040, 0x14000652d00}, 0x1400263e6c0)
        /Users/coxley/.go/pkg/mod/google.golang.org/grpc@v1.62.1/server.go:1801 +0xac4
google.golang.org/grpc.(*Server).serveStreams.func2.1()
        /Users/coxley/.go/pkg/mod/google.golang.org/grpc@v1.62.1/server.go:1027 +0x84
created by google.golang.org/grpc.(*Server).serveStreams.func2 in goroutine 8622
        /Users/coxley/.go/pkg/mod/google.golang.org/grpc@v1.62.1/server.go:1038 +0x138

This PR ensures that google.protobuf.Timestamp messages are converted to time.Time early in decodeRowData.

It also fixes a bug for RECORD columns containing TIMESTAMP cells — but it depends on goccy/go-zetasqlite#232 to make the test pass.

Test Plan

Added a new test case that reproduces the problem, and is fixed with these changes:

> go test ./...
?       github.com/goccy/bigquery-emulator/cmd/bigquery-emulator        [no test files]
?       github.com/goccy/bigquery-emulator/internal/connection  [no test files]
?       github.com/goccy/bigquery-emulator/internal/contentdata [no test files]
?       github.com/goccy/bigquery-emulator/internal/logger      [no test files]
?       github.com/goccy/bigquery-emulator/internal/metadata    [no test files]
?       github.com/goccy/bigquery-emulator/internal/types       [no test files]
ok      github.com/goccy/bigquery-emulator/server       2.749s
?       github.com/goccy/bigquery-emulator/types        [no test files]

[coxley]

I assume @goccy is the best maintainer to review? Thanks in advanced!