Move command invalidation from decoration addon to command detection capability

[Tyriar]

We currently have this which runs on the renderer process only:

vscode/src/vs/workbench/contrib/terminal/browser/xterm/decorationAddon.ts

Lines 174 to 180 in 483ec48

	this._commandFinishedListener = capability.onCommandFinished(command => {
	if (command.command.trim().toLowerCase() === 'clear' || command.command.trim().toLowerCase() === 'cls') {
	this.clearDecorations();
	return;
	}
	this.registerCommandDecoration(command);
	});

What we should do instead to ensure these changes carry over across reconnects is to mark commands as invalid or something and fire an event inside the command detection capability. The decorations addon would then listen to it and react accordingly.

[Tyriar]

Additionally, using clear and cls here will be inherently flaky, running cls in bash for example will do nothing.

A similar workaround was added to PartialCommandDetectionCapability yesterday which checks which erase in display was used:

vscode/src/vs/platform/terminal/common/capabilities/partialCommandDetectionCapability.ts

Lines 37 to 43 in ab56599

	this._terminal.parser.registerCsiHandler({ final: 'J' }, params => {
	if (params.length >= 1 && (params[0] === 2 || params[0] === 3)) {
	this._clearCommandsInViewport();
	}
	// We don't want to override xterm.js' default behavior, just augment it
	return false;
	});