Widgets/edit field to text area

[wiktor-obrebski]

This PR migrate commonly used EditField widget to be based on TextArea component.
Its inherits all TextArea features in one line mode, keeping original interface of EditField widget.

Also, I polished one line mode of TextArea to display cp437 character (◙) instead of remove them.

[myk002]

approved, but holding off on merge until after 50.15-r2 is tagged since we're so close to release

[myk002]

I think I was mimicking readline behavior before, but I agree with this change since it matches browser edit field behavior.

[myk002]

From testing, there is an issue with focus setting in gui/launcher. If you do a history search (via Alt-s or by clicking on the search widget) and then right click or hit esc to go back to editing the commandline, no widget has focus and key input is lost. Are the onunfocus handlers being run correctly?

Also, for activatable edit fields that you can click to set focus and start editing, like the blueprint name in gui/blueprint, the existing text will become highlighted from the end of the word to the place where you clicked. It would make more sense to highlight the entire string on activation or not highlight anything and ignore the first click, leaving the cursor at the end of the string.

However, if we highlight everything on focus, we should fix another (existing) behavior I noticed when I double clicked to highlight a word, then hit an arrow key. Currently, the cursor gets positioned relative to the beginning of the word when you do this. If a word is highlighted and I hit the left arrow, I'd expect the cursor to be at the beginning of the word, not one position to the left of the word. If a word is highlighted and I hit the right arrow key, I expect the cursor to be just after the last letter of the word, not one position to the right from the first letter of the word.

testing shows some issues that need to be fixed first

[myk002]

Focus is fixed for gui/launcher and the partial-highlight-on-activate issue in gui/blueprint is fixed, but now I'm seeing a few new issues:

• in gui/launcher you can no longer iteratively search the history. Repro steps:
  • type something that will match multiple elements in your history
  • hit Alt-s to search. first match shows on the commandline
  • hit Alt-s again. in HEAD, the next matched commandline in the history will show. with this PR, the matched commandline doesn't change
• in gui/blueprint, the edit field contents can revert to an incorrect string. Repro steps:
  • start gui/blueprint
  • edit the name field to something unique and hit enter to commit
  • re-select the name field and cancel out
  • expected: the string does not change; actual: the string is cleared to the default initial value
  • I If you commit a new string again, then re-activate and cancel, you'll get the first string you entered up at step 2. I suspect the onfocus/onunfocus behavior is different from the original EditField such that gui/blueprint is not getting the events at the same time as before.