feat(bigtable): implement PrepareQuery in DataConnectionImpl

[mpeddada1]

Introducing implementation to create a PreparedQuery through DataConnectionImpl#PrepareQuery.

[codecov]

Codecov Report

❌ Patch coverage is 97.95918% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 93.10%. Comparing base (30acc3c) to head (d1dc7fa).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
...le/cloud/bigtable/internal/data_connection_impl.cc	94.11%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #15661      +/-   ##
==========================================
- Coverage   93.11%   93.10%   -0.01%     
==========================================
  Files        2439     2439              
  Lines      224091   224136      +45     
==========================================
+ Hits       208655   208680      +25     
- Misses      15436    15456      +20     

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[mpeddada1]

demo-fedora-pr is resulting in the following error when emplace is used:

 /workspace/google/cloud/bigtable/internal/data_connection_impl.cc: In member function 'virtual google::cloud::v2_44::StatusOr<google::cloud::bigtable::v2_44::PreparedQuery> google::cloud::bigtable_internal::v2_44::DataConnectionImpl::PrepareQuery(const google::cloud::bigtable::v2_44::PrepareQueryParams&)':
Step #2: /workspace/google/cloud/bigtable/internal/data_connection_impl.cc:629:36: error: 'class google::protobuf::Map<std::__cxx11::basic_string<char>, google::bigtable::v2::Type>' has no member named 'emplace'
Step #2:   629 |     request.mutable_param_types()->emplace(p.first, p.second.type());
Step #2:       |                                    ^~~~~~~

On the other hand, the demo-debian-bookwork-pr results in the following error when insert is used:

/workspace/google/cloud/bigtable/internal/data_connection_impl.cc:629:42: error: no matching function for call to 'google::protobuf::Map<std::__cxx11::basic_string<char>, google::bigtable::v2::Type>::insert(std::pair<std::__cxx11::basic_string<char>, google::bigtable::v2::Type>)'
Step #2:   629 |     request.mutable_param_types()->insert(
Step #2:       |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^
Step #2:   630 |         std::make_pair(p.first, p.second.type()));

[scotthart]

We should check with the Bigtable team to see if we're correct in treating this RPC as non-idempotent.

[mpeddada1]

Hm that's a good point, will confirm if this the desired behavior (created #15663 for an immediate follow up)