feat: sql fast path impl

[stephaniewang526]

Expose backend query() method in the client when QueryJobConfiguration is supported by QueryRequest

cc: @gcasto

[codecov]

Codecov Report

Merging #509 into master will decrease coverage by 0.12%.
The diff coverage is 74.28%.

@@             Coverage Diff              @@
##             master     #509      +/-   ##
============================================
- Coverage     81.07%   80.94%   -0.13%     
- Complexity     1236     1261      +25     
============================================
  Files            78       79       +1     
  Lines          6334     6465     +131     
  Branches        705      735      +30     
============================================
+ Hits           5135     5233      +98     
- Misses          833      844      +11     
- Partials        366      388      +22     

Impacted Files	Coverage Δ	Complexity Δ
.../java/com/google/cloud/bigquery/BigQueryError.java	88.09% <ø> (ø)	14.00 <0.00> (ø)
.../com/google/cloud/bigquery/spi/v2/BigQueryRpc.java	82.60% <ø> (ø)	0.00 <0.00> (ø)
.../google/cloud/bigquery/spi/v2/HttpBigQueryRpc.java	4.90% <0.00%> (-0.05%)	2.00 <0.00> (ø)
...a/com/google/cloud/bigquery/BigQueryException.java	74.28% <64.28%> (-5.03%)	14.00 <5.00> (+3.00)	⬇️
...va/com/google/cloud/bigquery/QueryRequestInfo.java	73.13% <73.13%> (ø)	14.00 <14.00> (?)
...n/java/com/google/cloud/bigquery/BigQueryImpl.java	82.83% <80.00%> (-0.07%)	84.00 <6.00> (+7.00)	⬇️
...m/google/cloud/bigquery/QueryJobConfiguration.java	90.21% <100.00%> (+0.13%)	67.00 <1.00> (+1.00)

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[epavan123]

There are a number of warnings about uncovered lines. Please add tests to cover those.

[epavan123]

Hi,

Please hold on to the CL, I am looking into the interaction of this with some ongoing work to increase max row size limits.

[stephaniewang526]

There are a number of warnings about uncovered lines. Please add tests to cover those.

Added more test coverage wherever possible.