gopls/internal/golang: support parameter movement refactorings

Add "move parameter left" and "move parameter right" refactorings, via a
more general mechanism for change signature rewrites. As part of this,
define a flexible API for change signature, though only parameter
permutation is currently supported.

For golang/go#38028

Change-Id: I14142d5456904836402d94130f6ee1e32a19066c
Reviewed-on: https://go-review.googlesource.com/c/tools/+/581535
LUCI-TryBot-Result: Go LUCI <[email protected]>
Reviewed-by: Alan Donovan <[email protected]>

Author: findleyr

gopls/doc/release/v0.17.0.md

@@ -13,6 +13,15 @@
 
 # New features
 
+## Change signature refactoring
+
+TODO(rfindley): document the state of change signature refactoring once the
+feature set stabilizes.
+
+## Improvements to existing refactoring operations
+
+TODO(rfindley): document the full set of improvements to rename/extract/inline.
+
 ## Extract declarations to new file
 
 Gopls now offers another code action,