internal/lsp: fill in ServerInfo in the initialize response
internal/lsp: fill in ServerInfo in the initialize response

Fixes golang/go#38459

Change-Id: I98476ddc35c4ab2c43145083149454875cb4b041
Reviewed-on: https://go-review.googlesource.com/c/tools/+/228398
Run-TryBot: Hyang-Ah Hana Kim <d7e82c3c07f92613bcbf9a1e88f6b96c13caa3b0@gmail.com>
TryBot-Result: Gobot Gobot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Reviewed-by: Rebecca Stambler <d7cf11e5f299d88ea8348366a9fc4f7c335c3afa@golang.org>

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