internal/lsp: stop requiring a .go extension for all Go files
internal/lsp: stop requiring a .go extension for all Go files

This change should fix the TryBot failures exposed by
https://golang.org/cl/181317.

Updates golang/go#31561

Change-Id: Ie77c9e3bfd6825dcd2608523e72f804f81d3f48c
Reviewed-on: https://go-review.googlesource.com/c/tools/+/181546
Run-TryBot: Rebecca Stambler <d7cf11e5f299d88ea8348366a9fc4f7c335c3afa@golang.org>
TryBot-Result: Gobot Gobot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Reviewed-by: Ian Cottrell <52376736e5e84615ec49f9c1843b8acc178b1d8d@google.com>

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