* feat: refactor aws and identity pool credentials to use suppliers

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* updating suppliers to use options objects

* updating docs

* moved transporter to context object and deprecated consts

* fix imports

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…h custom suppliers. (#1783)

* feat: adds support for users to build credentials with custom suppliers

Also adds default values to make it easier to instantiate credentials in code.

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* responding to review comments

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* docs: adding documentation for programmatic auth feature

* fix typos

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* add audience placeholder

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# Conflicts:
#	src/auth/awsclient.ts
#	src/auth/identitypoolclient.ts