feat: Add support for the parent expression and fix integration tests error

[yvonnep165]

• Add support for the parent expression

Ported from firebase/firebase-js-sdk#9773

• Change integration tests testPipelineInTransactions and testNestedFields due to the changes of nested field handling by backend
• Change integration test testChecks due to change in backend implementation - treat applying an array operation to a non-array field as a strict evaluation error. Therefore, isError() now returns true, and ifError() triggers, returning fallback handler
• Change PipelineUtils.java where it automatically generated aliases with dots for nested fields, to fix error for test performsAggregationsOnNestedMapValues in ITQueryAggregationsTest.java