Implement `impl ... for ...`

[NobodyForNothing]

Changes

Generates methods when implementing traits for structs.

Fixes #1894

Also Fixes a typo on the website.

Checklist

• [X] An issue to be fixed by this PR is listed above.
• [X] New tests are added to ensure new features are working. Please refer to this page to see how to add a test.
• [ ] ./frb_internal precommit --mode slow (or fast) is run (it internal runs code generator, does auto formatting, etc).
• [ ] If this PR adds/changes features, documentations (in the ./website folder) are updated.
• [ ] CI is passing. Please refer to this page to see how to solve a failed CI.

Running ./frb_internal precommit --mode slow locally always results in compilation errors/panics and changes a bunch of tracked files, even on the master branch. It would be great if someone could help me resolve this.

I'm also unsure how to use twin tests and left that part out.

[welcome[bot]]

Hi! Thanks for opening this pull request! :smile:

[fzyzcjy]

Running ./frb_internal precommit --mode slow locally always results in compilation errors/panics and changes a bunch of tracked files, even on the master branch. It would be great if someone could help me resolve this.

Then maybe ./frb_internal generate-internal-frb-example-pure-dart ; ./frb_internal precommit-generate

I'm also unsure how to use twin tests and left that part out.

It is auto generated (by commands above), no worries