Add title_align config directive

Controls the window titles alignment in title bars. Possible values are:
- left
- center
- right

Co-authored-by: Orestis Floros <orestisf1993@gmail.com>
- Made title_align a config directive instead of a command. Helps with
some tree_render() issues we had.
- Made title_max_width the same for all 3 cases.
- Modified title offset calculations and added explanations for each
case.
- Append title_padding to mark_width if a mark exists.

Fixes #1750

parser-specs/config.spec

@@ -45,6 +45,7 @@ state INITIAL:
   'fake_outputs', 'fake-outputs'           -> FAKE_OUTPUTS
   'force_display_urgency_hint'             -> FORCE_DISPLAY_URGENCY_HINT
   'focus_on_window_activation'             -> FOCUS_ON_WINDOW_ACTIVATION
+  'title_align'                            -> TITLE_ALIGN
   'show_marks'                             -> SHOW_MARKS
   'workspace'                              -> WORKSPACE
   'ipc_socket', 'ipc-socket'               -> IPC_SOCKET
@@ -248,6 +249,11 @@ state FORCE_DISPLAY_URGENCY_HINT:
   duration_ms = number
       -> FORCE_DISPLAY_URGENCY_HINT_MS
 
+# title_align [left|center|right]
+state TITLE_ALIGN:
+  alignment = 'left', 'center', 'right'
+      -> call cfg_title_align($alignment)
+
 # show_marks
 state SHOW_MARKS:
   value = word