proposal: elide "src" in module import paths

[mcandre]

I would like to be able to nest assorted .go files in a "src" directory, which may not constitute separate logical sub-modules, without having to add "src", nor aliases, to the resulting import paths.

I tend to use a lot of top-level non-go files, such as linter configurations. My .go files are interleaved with these, which makes project navigation more difficult for new project ontributors.

Some of my .go files could reasonably be bundled into a common sub-module. But Not all of them.

I prefer a universal, repeatable project structure. For example, I nest my importable Rust code in a "src" subdirectory. I nest my importable Java code in "a src/..." subdirectory. I nest my importable shell code in a "lib" directory. I would love for the go module system to allow for similar subdirectory elision in import paths.

[seankhliao]

Duplicate of #34055