Extend support for batch operation mocking / assertions

[sweep-ai]

Description

This PR extends the support for batch operation mocking and assertions in the pgxmock package. It addresses issue #149 by modifying the SendBatch method, adding a new type ExpectedBatch, and introducing a new method ExpectBatch to the pgxmock type. Additionally, the ExpectationsWereMet method is updated to check if all expected batch operations were met.

Summary of Changes

• Modified the SendBatch method in pgxmock.go to return mock batch results based on the queued expectations.
• Added a new type ExpectedBatch in pgxmock.go to represent an expected batch operation, including the expected SQL statements and their arguments, as well as methods to set the expected results or errors.
• Added a new method ExpectBatch in pgxmock.go to queue an expected batch operation. This method returns an ExpectedBatch instance that can be configured in tests.
• Updated the ExpectationsWereMet method in pgxmock.go to also check if all expected batch operations were met.
• Added unit tests in pgxmock_test.go to cover the new ExpectBatch method and the modified SendBatch method. These tests cover various scenarios, including successful batch operations, batch operations that result in errors, and batch operations that do not meet the expectations.

Fixes #149.

---

To checkout this PR branch, run the following command in your terminal:

git checkout sweep/batch-operation-mocking

To get Sweep to edit this pull request, leave a comment below or in the code. Leaving a comment in the code will only modify the file but commenting below can change the entire PR.