Added support for Tokenlist columns

[n-d-joshi]

This PR supports the following for PG dialect:

1. Tokenlist type for columns.
2. Hidden attribute for columns.

Did manual testing by creating a test database and running the Cloud_Spanner_to_GCS_Avro template to export and then imported successfully into a new database using a locally built GCS_Avro_to_Cloud_Spanner. The imported database had the TOKENLIST columns along with Hidden attributes.

[n-d-joshi]

R: @atask-g

[codecov]

Codecov Report

Attention: Patch coverage is 80.00000% with 2 lines in your changes missing coverage. Please review.

Project coverage is 46.75%. Comparing base (5cda88d) to head (800a0ad).
Report is 12 commits behind head on main.

Files with missing lines	Patch %	Lines
...oogle/cloud/teleport/spanner/common/SizedType.java	66.66%	0 Missing and 1 partial ⚠️
.../apache/beam/sdk/io/gcp/spanner/SpannerSchema.java	50.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #2144      +/-   ##
============================================
+ Coverage     46.72%   46.75%   +0.03%     
- Complexity     3978     3980       +2     
============================================
  Files           872      873       +1     
  Lines         51687    51879     +192     
  Branches       5402     5430      +28     
============================================
+ Hits          24151    24257     +106     
- Misses        25818    25897      +79     
- Partials       1718     1725       +7     

Components	Coverage Δ
spanner-templates	68.65% <87.50%> (-0.14%)	⬇️
spanner-import-export	65.65% <87.50%> (+0.05%)	⬆️
spanner-live-forward-migration	76.49% <ø> (-1.02%)	⬇️
spanner-live-reverse-replication	78.39% <ø> (ø)
spanner-bulk-migration	87.87% <ø> (+<0.01%)	⬆️

Files with missing lines	Coverage Δ
...oud/teleport/spanner/DdlToAvroSchemaConverter.java	93.03% <ø> (ø)
...com/google/cloud/teleport/spanner/common/Type.java	90.32% <100.00%> (+0.13%)	⬆️
.../com/google/cloud/teleport/spanner/ddl/Column.java	84.11% <100.00%> (+0.93%)	⬆️
...oogle/cloud/teleport/spanner/common/SizedType.java	91.84% <66.66%> (+0.13%)	⬆️
.../apache/beam/sdk/io/gcp/spanner/SpannerSchema.java	66.05% <50.00%> (+0.63%)	⬆️

... and 17 files with indirect coverage changes

[atask-g]

Looks great! Can you also also add a pg specific test similar to searchIndexes() to InformationSchemaScannerIT.java? Also, consider adding a test to DdlTest.java similar to testSearchIndex() which should improve the code coverage stats.

[n-d-joshi]

@atask-g, as discussed offline - will follow up with these tests in the next PR once the rest of the changes are also done so it will help to get comprehensive coverage. Thanks for the review.

[darshan-sj]

Looks good.

You will need to raise a PR in apache/beam also similar to this apache/beam#32038

[Abacn]

Please sync the change to Beam's SpannerIO : https://github.com/apache/beam/blob/master/sdks/java/io/google-cloud-platform/src/main/java/org/apache/beam/sdk/io/gcp/spanner/SpannerSchema.java

LocalSpannerIO does not admit changes that not already in Beam's SpannerIO, and is going to be teardown

#1429 will affect part of the functionality added in this PR