Add tab bar clip mode

[PiCode9560]

Added tab bar clip mode which determine how the inspector tab bar handle tabs overflows.

Related: #27

• Added a new editor setting: tab clip mode (maybe it's better called “tab bar clip mode”?) which has 3 options:
  • scroll: if the tabs overflowed, a scroll bar will show up so that you can scroll to the hidden tabs. (Probably way better for it to work like the built-in tab bar scrolling)
  • Clip text: if the tabs overflowed, the text in the tabs will be clipped to make space for the hidden tabs. (Currently not working at all)
  • Flow (Maybe better called something like “multi-row”?): If the tabs overflowed, the hidden tabs will be placed in a new row of tabs.
• Change the tab bar to a custom one so that it is easier to customize.

TODO:

• Fix the custom tab bar is broken if the inspector is placed on the left dock.
• Change the scroll mode to work like the built-in tab bar.
• Add clip text mode.
• Fix tab not selecting the same one when selecting different node.