fix(terminal): Line height, colour palette and tab names (#141)

* fix(terminal): Line height, colour palette and tab names

- Line height: with "Use editor font" the terminal took the editor's roomier
  line height (about 1.33 cells), stretching ASCII art and box drawing. It now
  always uses Settings › Tools › Terminal › Line height (default 1.0); that
  field moves out of the "Use editor font" group since it applies either way.
- Colours: the terminal gets its own --terminal-ansi-* palette (the light and
  Darcula terminal colours); the Run console keeps --ansi-*. High-contrast and
  palette themes keep their console colours. Colours below a 4.5:1 contrast
  with the background are adjusted (xterm's minimumContrastRatio), so yellow
  stays readable on white.
- Tab names: tabs keep their default name ("Local", "Local (2)") at the prompt
  and show the title a program sets only while a command runs. Shell
  integration now marks command start and end (OSC 133 C / D) for zsh,
  bash 4.4+ (PS0) and fish.

* fix(themes): Document the terminal ANSI palette for theme plugins

The --terminal-ansi-* tokens belong in a theme's editor colour scheme, like
--ansi-*. The theme plugin template sets them and the token reference lists them.

scripts/theme/tokens.ts

@@ -23,7 +23,7 @@ export interface TokenGroup {
 }
 
 /** tokens.css sections that IntelliJ keeps in an editor scheme (`.icls`). */
-export const SCHEME_GROUPS = ["syntax", "editor", "ANSI palette"];
+export const SCHEME_GROUPS = ["syntax", "editor", "ANSI palette", "terminal ANSI palette"];
 
 const LIGHT_SELECTOR = ':root[data-theme="light"]';