Go to test

[AdrienLemaire]

Describe the feature
On VScode, an option "go to tests" exists, that will:

• navigate the user to the related test file if exists,
• else create the directory structure and filename, and fill the new file with boilerplate to get started writing the test.

It would be nice to have the option to :CocCommand flutter.goToTests and get the same behavior on vim :)

[dkbast]

yes this would be amazing - a next logical step would be that renaming/moving one file also results in renaming/moving the other file. This could maybe also be done via a custom_lint rule e.g. "have matching paths and names for test and implementation"'