Improve handling of nested arrays and arrays of nullable values

[hazefully]

This PR improves handling of the user including nested arrays as a selected element, which is not possible due to the limitation of record-layer discussed in #4167, by rejecting the query at parsing time due to the lack of support for nested arrays. If the nested arrays are instead used to evaluate some other values (for example in a comparison), it is allowed as in https://github.com/hazefully/fdb-record-layer/blob/e19cb847765c7801d0d2e0d47ed0e0e374874d57/yaml-tests/src/test/resources/arrays-operators.yamsql#L259-L262.

The PR also improves handling of constructing arrays using underlying nullable values, by adding a promotion to the non-nullable variant of the same type, as arrays with non-nullable elements are also not supported. This used to cause issues in continuations, when attempting to parse the ResultSetMetadata that is serialised in the continuation. In addition, the array construction is migrated to make use of the __internal_array built-in function since it now supports promoting record types properly while computing the max type of its elements.

Finally, the PR contains an improvement to fdb-relational-grpc to maintain the struct type names in the ResultSetMetadata to support asserting on these names in yaml-tests. The struct names were already maintained with embedded connections, so this makes the gRPC connection maintain the struct type names as well.

[github-actions]

📊 Metrics Diff Analysis Report

Summary

• New queries: 1
• Dropped queries: 0
• Plan changed + metrics changed: 0
• Plan unchanged + metrics changed: 0

ℹ️ About this analysis

This automated analysis compares query planner metrics between the base branch and this PR. It categorizes changes into:

• New queries: Queries added in this PR
• Dropped queries: Queries removed in this PR. These should be reviewed to ensure we are not losing coverage.
• Plan changed + metrics changed: The query plan has changed along with planner metrics.
• Metrics only changed: Same plan but different metrics

The last category in particular may indicate planner regressions that should be investigated.

New Queries

Count of new queries by file:

• yaml-tests/src/test/resources/arrays.metrics.yaml: 1