feat: switch android_fn! to a proc_macro

[amrbashir]

What kind of change does this PR introduce?

• Bugfix
• Feature
• Docs
• New Binding issue #___
• Code style update
• Refactor
• Build-related changes
• Other, please describe:

Does this PR introduce a breaking change?

• Yes, and the changes were approved in issue #___
• No

Checklist

• When resolving issues, they are referenced in the PR's title (e.g fix: remove a typo, closes #___, #___)
• A change file is added if any packages will require a version bump due to this PR per the instructions in the readme.
• I have added a convincing reason for adding this feature, if necessary

Other information

This is rewrite was due to happen soon and it allows us to:

1. handle _ in package name and escape it properly, instead of relying on users to pass it escaped.
2. support variadic arguments to functions (encountered while implementing callback for when document.title is changed? wry#804)

[wusyong]

LGTM, but you should add doc on those macro if we want to expose this.
And also add tao-macro to workspace and our CI config

[wusyong]

Or we could make this into separate repo and crate then.

[amrbashir]

LGTM, but you should add doc on those macro if we want to expose this.
And also add tao-macro to workspace and our CI config

will do, I was just looking for a first review for the macro code.

Or we could make this into separate repo and crate then.

I'd rather keep this in the repo.

[wusyong]

I'd rather keep this in the repo.

Alright! We keep int this repo then. I'm not concerned about the implementation since it's fairly short but I treat proc macro as a different DSL. A comprehensive documentation is required.