Enhancement request: hoist keepNames implementation

when c8 wraps files transformed via esbuild (i.e. like via tsx), use of the keepNames option (which tsx uses by default) can add a line of unreachable code when the function is declared after a return statement, as demonstrated here:

https://github.com/yaacovcr/esbuild-sourcemap-test

This can cause coverage issues with esbuild/tsx.

It would be great if the keepNames options for esbuild could set the name of the function at the top of the relevant scope.

Start with the linked esbuild-sourcemap-test reproduction and inspect how the keepNames option handles functions declared after return statements in transformed files. Confirm the unreachable code and coverage impact with the esbuild/tsx scenario; done means the function name is assigned at the top of the relevant scope without adding unreachable code.

Written by the indexing model from the issue text.