internal/lsp: check URIs of all workspace folders
internal/lsp: check URIs of all workspace folders

We can prevent crashing on non-file URIs by checking the URIs of the
workspace folders, as well as the root URI.

Updates golang/go#40272

Change-Id: Ieddc6d6053fbb3d61e4c26fc8831c092328f6f33
Reviewed-on: https://go-review.googlesource.com/c/tools/+/244602
Run-TryBot: Rebecca Stambler <d7cf11e5f299d88ea8348366a9fc4f7c335c3afa@golang.org>
TryBot-Result: Gobot Gobot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Reviewed-by: Heschi Kreinick <e89ab2b172855aa0ad01c40c4d8a3535a61ac68a@google.com>

golang/tools,golang/tools,golang/tools,golang/tools,golang/tools