lint: homogenize operations and minor fixes (gocritic)

Apply GoDoc comment policy (comments for humans should have a space
after the //; machine-readable comments shouldn't)

Use strings.ReplaceAll instead of strings.Replace when appropriate

Remove if/else chains by replacing them with switches

Use short assignment/increment notation

Replace single case switches with if statements

Combine else and if when appropriate

Signed-off-by: Moritz Poldrack <moritz@poldrack.dev>
Acked-by: Robin Jarry <robin@jarry.cc>

commands/msg/read.go

@@ -102,11 +102,12 @@ func (FlagMsg) Execute(aerc *widgets.Aerc, args []string) error {
 			flagChosen = true
 		}
 	}
-	if toggle {
+	switch {
+	case toggle:
 		actionName = "Toggling"
-	} else if enable {
+	case enable:
 		actionName = "Setting"
-	} else {
+	default:
 		actionName = "Unsetting"
 	}
 	if optind != len(args) {