BUG: Fix boolean column indexer for single-column EA-backed ExtensionBlocks

[Ankita7033]

• [ x] closes #xxxx (Replace xxxx with the GitHub issue number)
• [x ] Tests added and passed if fixing a bug or adding a new feature
• [ x] All code checks passed.
• Added type annotations to new arguments/methods/functions.
• [x ] Added an entry in the latest doc/source/whatsnew/vX.X.X.rst file if fixing a bug or adding a new feature.
• [x ] I have reviewed and followed all the contribution guidelines
• [x ] If I used AI to develop this pull request, I prompted it to follow AGENTS.md.

[Ankita7033]

Implemented a fix for the reported NotImplementedError when using a boolean column indexer on a single-column EA-backed DataFrame.

Validation

• Added a regression test covering both .loc and .iloc.
• Ran:

  python -m pytest pandas/tests/frame/indexing/test_indexing.py