…entials (#1496)

* feat: refactor AWS and identity pool credentials to use suppliers (#1484)

* feat: refactor aws and identity pool credentials to use supplier framework

* Linting

* changing class types

* linting

* remove unused import

* Fix typing

* add docstring and fix casing

* feat: Adds support for custom suppliers in AWS and Identity Pool credential instantiation (#1494)

* feat: refactor aws and identity pool credentials to use supplier framework

* Linting

* changing class types

* linting

* remove unused import

* Fix typing

* add docstring and fix casing

* feat: adds support for passing suppliers to credentials.

* fixes merge issues and adds _has_custom_supplier method

* adds _has_custom_supplier function to identity_pool

* Update google/auth/external_account.py

Co-authored-by: Carl Lundin <108372512+clundin25@users.noreply.github.com>

* Apply suggestions from code review

Co-authored-by: Carl Lundin <108372512+clundin25@users.noreply.github.com>

* Respond to comments and fix docs

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Co-authored-by: Carl Lundin <108372512+clundin25@users.noreply.github.com>

* docs: add documentation for suppliers (#1495)

* docs: update docs for programmatic

* add space

* update user guide

* update docs

* Apply suggestions from code review

Co-authored-by: Leo <39062083+lsirac@users.noreply.github.com>

* Update docs

* Add docs about context and request

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Co-authored-by: Carl Lundin <108372512+clundin25@users.noreply.github.com>
Co-authored-by: Leo <39062083+lsirac@users.noreply.github.com>