Fix#8839: Cannot select item from command selector

[Clem-Fern]

Hi @Eugeny, I hope all is well with you.

Fix #8839 : This PR aims to fix the issue #8839. Commit d354520 avoid the selectedIndex value to be NaN cause of modulo (this.selectedIndex + this.filteredOptions.length) % this.filteredOptions.length when filteredOptions is empty. Once selectedIndex in NaN, the OnFilterChange method is no longer able to do operation with selectedIndex which cause the selector to do not have any element selected any more even if the filter is empty or matches elements.

ad3b03c: I also added a small feature on PageUp & PageDown event to limit the number of elements being skipped when the key is press.

tabby/tabby-core/src/components/selectorModal.component.ts

Lines 35 to 40 in 634d88d

	if (event.key === 'PageUp' || event.key === 'ArrowUp' && event.metaKey) {
	this.selectedIndex -= Math.min(10, Math.max(1, this.selectedIndex))
	event.preventDefault()
	} else if (event.key === 'PageDown' || event.key === 'ArrowDown' && event.metaKey) {
	this.selectedIndex += Math.min(10, Math.max(1, this.filteredOptions.length - this.selectedIndex - 1))
	event.preventDefault()

On 1.0.197:
Open selector. Select the second element before the end and press PageDown.
The eighth from the start will be the one selected now.

With this PR:
Open selector. Select the second element before the end and press PageDown.
The last element of the list will be the one selected now.
Press PageDown again.
It will select the first element from the top of the list.
Same inverse behavior on PageUp.

As always, feel free to ask me if any change are needed !

[Eugeny]

LGTM, great job!