various: add golangci-lint, fix issues (#7905)

This adds an initial and intentionally minimal configuration for
golang-ci, fixes the issues reported, and adds a GitHub Action to check
new pull requests against this linter configuration.

Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: I8f38fbc315836a19a094d0d3e986758b9313f163

util/mak/mak.go

@@ -26,7 +26,7 @@ func Set[K comparable, V any, T ~map[K]V](m *T, k K, v V) {
 // the field to be defined after they decode the JSON.)
 //
 // Deprecated: use NonNilSliceForJSON or NonNilMapForJSON instead.
-func NonNil(ptr interface{}) {
+func NonNil(ptr any) {
 	if ptr == nil {
 		panic("nil interface")
 	}

util/winutil/policy/policy_windows.go

@@ -147,4 +147,3 @@ func SelectControlURL(reg, disk string) string {
 	}
 	return def
 }
-