x/tools/gopls: add examples from <pkg>/examples_test.go to hover info

[abenz1267]

Hello everyone,

i'd be a good addition to add an option to show code examples for hover. I figured out pkg.go.dev simply parses the packages example_test.go file/function. So f.e. regexp.ReadAllString -> regexp/examples_test.go ExampleRegexp_ReadAllString.

I tried a very naive approach just as a POC and got this result:

Regards