feat: COPY my_table TO STDOUT

[olavloite]

Adds support for COPY my_table TO STDOUT statements to allow copying data from a Cloud Spanner table to another Cloud Spanner table in the same or different database, or to a table in a PostgreSQL database.

[codecov]

Codecov Report

Merging #269 (011e9ef) into postgresql-dialect (ce01b5c) will increase coverage by 0.20%.
The diff coverage is 83.56%.

@@                   Coverage Diff                    @@
##             postgresql-dialect     #269      +/-   ##
========================================================
+ Coverage                 80.87%   81.08%   +0.20%     
- Complexity                 1167     1223      +56     
========================================================
  Files                        95       99       +4     
  Lines                      3943     4208     +265     
  Branches                    488      511      +23     
========================================================
+ Hits                       3189     3412     +223     
- Misses                      578      616      +38     
- Partials                    176      180       +4     

Flag	Coverage Δ
all_tests	81.08% <83.56%> (+0.20%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...e/cloud/spanner/pgadapter/parsers/ArrayParser.java	71.64% <ø> (ø)
.../cloud/spanner/pgadapter/parsers/BinaryParser.java	72.72% <ø> (ø)
...cloud/spanner/pgadapter/parsers/BooleanParser.java	86.11% <ø> (ø)
...le/cloud/spanner/pgadapter/parsers/DateParser.java	90.00% <ø> (ø)
.../cloud/spanner/pgadapter/parsers/DoubleParser.java	82.60% <ø> (ø)
...cloud/spanner/pgadapter/parsers/IntegerParser.java	72.72% <ø> (+4.54%)	⬆️
...le/cloud/spanner/pgadapter/parsers/LongParser.java	82.60% <ø> (ø)
...cloud/spanner/pgadapter/parsers/NumericParser.java	84.61% <ø> (ø)
...google/cloud/spanner/pgadapter/parsers/Parser.java	80.72% <ø> (ø)
.../cloud/spanner/pgadapter/parsers/StringParser.java	92.85% <ø> (ø)
... and 23 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update ce01b5c...011e9ef. Read the comment docs.