Add Tmux strategy

[gerardroche]

Tmux Settings :new:

Configure Tmux settings for running tests in a tmux pane:

Setting	Type	Default	Description
phpunit.tmux_clear	bool	true	Clear the terminal screen before running tests.
phpunit.tmux_clear_scrollback	bool	false	Clear the terminal's scrollback buffer using the extended "E3" capability.
phpunit.tmux_target	string	:.	Specify the session, window, and pane which should be used to run tests. Format: {session}:{window}.{pane} The default means the current pane. For example, :{start}.{top} would mean the current session, lowest-numbered window, top pane. See Tmux documentation for target usage.

Example: Run tests in a Tmux pane.

{
    "phpunit.strategy": "tmux",
    "phpunit.options": { "colors": true, "no-coverage": true }
}

Tip: Use the no-coverage option with the Command Palette PHPUnit: Toggle --no-coverage to turn code coverage on and off for quicker test runs when you just don't need the code coverage report.

Example: Run tests in current session, lowest-numbered window, and top pane

{
    "phpunit.strategy": "tmux",
    "phpunit.tmux_target": ":{start}.{top}"
}

The target accepts the format {target-session}:{target-window}.{target-pane}. The default is :., which means the current pane.

See Tmux documentation for more details on the target usage.

See README.md for usage.