Preserve '\n' terminal keystrokes

Add setting for passing env var to terminal.

* Seed terminal find widget with current selection

Fixes #29712

Use the current selection as the search when we first show the find widget for the terminal

* Making requested changes

* Set TERM_PROGRAM in terminal

Fixes #29426

Sets the TERM_PROGRAM and TERM_PROGRAM_VERSION environment variables for the integrated terminal

* Use constant name for TERM_PROGRAM

* Shrink terminal find widget

Shrink the terminal find widget to fit within the max terminal size

* Added padding

* Match current size

Fixes #29788