Split editor_ui into editor_ui and editor_tabs

[rewin123]

Currently, the ui code is over-complicated and different related parts of it are scattered in random places. For example tabs logic is in editor_tab.rs lib.rs uiplugin.rs For simplification I suggest to put all core logic of dock/tabs systems in a separate crate, independent of any other space* crate. This will greatly increase both bug finding, testability and flexibility of the editor

• [x] Split crate
• [x] Make tab name not specific. Allow to use any enum for tab name
• [x] Move sizing and colors modules out of editor_tab crate
• [x] Create own plugin for editor_tabs

[naomijub]

is this done?

[rewin123]

Yep