Enable more revive linter rules (#30608)

Noteable additions:

- `redefines-builtin-id` forbid variable names that shadow go builtins
- `empty-lines` remove unnecessary empty lines that `gofumpt` does not
remove for some reason
- `superfluous-else` eliminate more superfluous `else` branches

Rules are also sorted alphabetically and I cleaned up various parts of
`.golangci.yml`.

routers/web/repo/pull_review.go

@@ -318,7 +318,6 @@ func UpdateViewedFiles(ctx *context.Context) {
 
 	updatedFiles := make(map[string]pull_model.ViewedState, len(data.Files))
 	for file, viewed := range data.Files {
-
 		// Only unviewed and viewed are possible, has-changed can not be set from the outside
 		state := pull_model.Unviewed
 		if viewed {