Update `README.md` to include detailed information about inputs, workflow permissions, build modes, and actions.

* **Inputs**: Add a section on inputs, including the `config` option, `languages`, `queries`, `packs`, `db-location`, `ram`, `threads`, and `source-root`.
* **Workflow Permissions**: Add a section on workflow permissions required for the actions.
* **Build Modes**: Add a section explaining the different build modes available for the actions (`none`, `autobuild`, `manual`).
* **Actions**: Add a section describing the different actions (`init`, `autobuild`, `analyze`, `upload-sarif`, `resolve-environment`, `start-proxy`) and how to use them, with links to the relevant documentation on GitHub.

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For more details, open the [Copilot Workspace session](https://copilot-workspace.githubnext.com/github/codeql-action?shareId=XXXX-XXXX-XXXX-XXXX).

Restructured the change to the README. Instead of directly including the
descriptions of the language inputs, added links to the inputs for each
action.