Make tabs look more consistent across all UIs

[fuzyll]

When we shipped the tab bar update last week, we created a new tab style that was applied to both the new tab bar and the global area. Unfortunately, this brings the total number of different tab styles in the product up to at least 4.

We should have a maximum of 1-2 different tab styles within the product to ensure we're using consistent design language when presenting tabbed layouts to users.

Places where we use tabs within the product, that I am aware of, include:

• [ ] Main Window
• [ ] New Tab (the new one currently on a test branch)
• [ ] Project Browser
• [ ] Plugin Manager
• [ ] Global Area
• [ ] Tags Sidebar Widget
• [ ] Debugger Sidebar Widget (Debugger)
• [ ] Edit Function Properties Dialog
• [ ] Open With Options Dialog
• [ ] Permission Manager Dialog (Enterprise)

There are also some places where we draw controls that appear to function like tabs, but actually aren't (and it's currently unclear to me if/how they should be handled):

• Settings View

[fuzyll]

There is also one place in Enterprise (the new Remote Browser dialog) that may have been adversely affected by this and needs to be looked at as well.

[psifertex]

Few others:

• [ ] Settings (has its own custom tab style, maybe distinct enough to leave alone, that's my vote?)
• [ ] Open with options
• [ ] Permission manager
• [ ] Debugger sidebar
• [ ] Edit Function Properties Dialog

[fuzyll]

I went back and actually made an exhaustive list by going through the codebase. The original comment has been edited to include this. I made sure it has everything from your comment (but I did put Settings in a separate list, since it doesn't use tabs - those are buttons and a menu).

I'm sure I've still missed something, but this should cover everything that most users will encounter.