Allow getter or method to have a *const Self first argument.

[karlseguin]

No description provided.

[krichprollsch]

@karlseguin, thanks for the PR.
Do you think you can add a corresponding case into https://github.com/lightpanda-io/zig-js-runtime/blob/main/src/tests/proto_test.zig?

[karlseguin]

@karlseguin, thanks for the PR. Do you think you can add a corresponding case into https://github.com/lightpanda-io/zig-js-runtime/blob/main/src/tests/proto_test.zig?

Done