feat(GCS+gRPC): more efficient CRC32C computations

[coryan]

Move the CRC32C and MD5 computations to the GrpcClient and RestClient. In the case of gRPC this allows us to compute the CRC32C checksum for each Write() message and then concatenate this checksum with the CRC32C checksum computed for the full object. That saves one of the most expensive computations in the gRPC uploads.

Fixes#11060

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This change is 

[codecov]

Codecov Report

Patch coverage: 99.58% and project coverage change: -0.01⚠️

Comparison is base (cbd2f66) 93.76% compared to head (f9aad7c) 93.76%.

Additional details and impacted files

@@ Coverage Diff @@## main #11070 +/- ##
==========================================
- Coverage 93.76% 93.76% -0.01% 
==========================================
Files 1730 1730 Lines 156241 156319 +78 ==========================================
+ Hits 146504 146573 +69 - Misses 9737 9746 +9 

Impacted Files	Coverage Δ
...le/cloud/storage/internal/object_write_streambuf.h	100.00% <ø> (ø)
google/cloud/storage/client.cc	85.80% <66.66%> (+0.09%)	⬆️
google/cloud/storage/hashing_options.cc	100.00% <100.00%> (ø)
google/cloud/storage/idempotency_policy_test.cc	100.00% <100.00%> (ø)
...d/storage/internal/async_accumulate_read_object.cc	91.01% <100.00%> (ø)
google/cloud/storage/internal/curl_client.cc	98.67% <100.00%> (ø)
google/cloud/storage/internal/curl_client_test.cc	99.48% <100.00%> (ø)
google/cloud/storage/internal/grpc_client.cc	98.89% <100.00%> (+0.45%)	⬆️
google/cloud/storage/internal/grpc_client_test.cc	100.00% <100.00%> (ø)
.../storage/internal/grpc_client_upload_chunk_test.cc	100.00% <100.00%> (ø)
... and 9 more

... and 7 files with indirect coverage changes

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