Clean up Fetch body data (#29451)

* Add `api.fetch.init_body_parameter`

* Move `body_readablestream` under `api.fetch.init_body_parameter`

* Add `api.Request.Request.init_body_parameter`

* Move `request_body_readablestream` under `api.Request.Request.init_body_parameter`

* Rename behavioral subfeature

* Create fetch options parameter

* Rewrite `init_foo_parameter` to `options_parameter.foo`

* Format

* Migrate standard-track-exceptions to new keys

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Co-authored-by: Claas Augner <495429+caugner@users.noreply.github.com>

Author: ddbeck