Add Bundle documentation for Amazon S3 and Google GCS providers

[shashbha14]

Closes#66986

Added a Bundles section to the Amazon and Google provider docs, following
the same pattern as the existing Git provider bundle documentation.
Changes:

• providers/amazon/docs/bundles/index.rst — documents S3DagBundle with
  configuration examples and parameter descriptions
• providers/google/docs/bundles/index.rst — documents GCSDagBundle with
  configuration examples and parameter descriptions
• Added Bundles entry to the Guides section in both provider index files
  I tried building the docs locally with Breeze but hit a Docker SIGBUS
  error during the CI image build. Will add rendered screenshots once
  resolved, or happy for a maintainer to verify the rendering.

I used Claude (claude.ai) as an AI assistant for parts of this implementation.

[ephraimbuddy]

LGTM

[eladkal]

@shashbha14 while git bundle does exist https://airflow.apache.org/docs/apache-airflow-providers-git/stable/bundles/index.html#bundles can you please edit it to cross reference the bundle docs in core? Ideally we should have the same info/format for the providers on that front. So if something is good on git lets reuse it in the other ones and vise-versa

[eladkal]

We also need new bundles to be present in provider.yaml otherwise the registry won't pick them up.

example for Git provider:

airflow/providers/git/provider.yaml

Lines 62 to 65 in 0778210

	bundles:
	- integration-name: GIT (Git)
	python-modules:
	- airflow.providers.git.bundles.git

[shashbha14]

@shashbha14 while git bundle does exist https://airflow.apache.org/docs/apache-airflow-providers-git/stable/bundles/index.html#bundles can you please edit it to cross reference the bundle docs in core? Ideally we should have the same info/format for the providers on that front. So if something is good on git lets reuse it in the other ones and vise-versa

Added a cross-reference to the core dag-bundles doc and simplified the format to match the git provider bundle docs.

[shashbha14]

We also need new bundles to be present in provider.yaml otherwise the registry won't pick them up.

example for Git provider:

airflow/providers/git/provider.yaml

Lines 62 to 65 in 0778210

	bundles:
	- integration-name: GIT (Git)
	python-modules:
	- airflow.providers.git.bundles.git

Both providers already have bundles registered in their provider.yaml files (Amazon at line 739, Google at line 934).