buildozer: support regex in move

Currently, the "move" command does not support specifying the value in terms of a regexp. I suppose this is because it prefers to support better matching for labels. Hot-changing it is really easy: I'm leaving the diff here if anybody needs it in the future, and searches the issues:

```diff
diff --git a/edit/edit.go b/edit/edit.go
index e56ee45..855d729 100644
--- a/edit/edit.go
+++ b/edit/edit.go
@@ -691,7 +691,8 @@ func RemoveFromList(li *build.ListExpr, item, pkg string, deleted **build.String
var all []build.Expr
for _, elem := range li.List {
if str, ok := elem.(*build.StringExpr); ok {
- if labels.Equal(str.Value, item, pkg) && (DeleteWithComments || !hasComments(str)) {
+ matched, err := regexp.Match(item, []byte(str.Value))
+ if matched && err == nil && (DeleteWithComments || !hasComments(str)) {
if deleted != nil {
*deleted = str
}
```

Apply and rebuild. `move` will take regexps instead of labels.

Start in edit/edit.go at RemoveFromList, using the diff in the issue as the implementation reference. Rebuild buildozer and verify that the move command accepts a regular expression and matches the intended list values without breaking existing label behavior.

Written by the indexing model from the issue text.