x/tools/gopls: support module-local renaming

[inliquid]

VS Code. Latest gopls code from master. Trying quite simple rename operation:

[stamblerre]

Right now, rename only works within a package and its tests. We are still working on a strategy for renaming packages in a module.

/cc @suzmue

[suzmue]

This is closely tied to issue #32869

Once find all references in the module level is supported, we should be able to global renaming.

[abitrolly]

Why modules are so important here? Is it possible to detect project root and scan all symbols the same way go build and go test ./... do?

[stamblerre]

The go command is quite different from gopls, but we will be able to scan the module root in a similar way. The reason that modules are relevant here is that the idea of renaming a symbol is different in module mode. You only want to rename a symbol within the module where it is defined, since clients depend on specific versions of your module, which will be found in the module cache. In $GOPATH mode, we would rename the symbol throughout the other projects in your $GOPATH.

[abitrolly]

When I did git clone for the tflint project I was editing and get project checkout, I didn't have to place the project somewhere on $GOPATH. Therefore it seems that it should be quite easy to cut all paths that lie outside of the project directory. If gopls can not detect which packages are native to project and which are external.