feat(tab-nav): adds optional closable functionality to individual tab-titles

[Elijbet]

Related Issue: #2620

Summary

handleTabTitleClose sequence is as follows:

if closed item is selected, fall back on the next
unless it's the last item, which falls back on previous
closing non-selected items doesn't affect the selected tab
last remaining item becomes disabled, if closable

• Added closed property
• Added closable property
• Added calciteInternalTabsClose event
• Added calciteTabsClose event
• Added t9n messages for Close text.
• Updated styling per new Figma specs
• Added tests

handleTabTitleClose keeps track of visibleTabTitlesIndices instead of having Dom queries filter out hidden. This helps to sync tabs with tab-titles using their corresponding ids set on the original render. visibleTabIndeces is an array of ids of the non-hidden tab-titles. When tab-title is closed this id is used to navigate to the next visible item. This makes figuring out what the next item should be when closing out of order is now more straightforward.

Tests coverage for

• simple closing behavior
• closing sequence behavior:

• when closing tab-titles in sequence 1 (first selected) through 4, tab-title and corresponding tab become hidden, and selection fallback is the next tab
• reverse fallback: when closing tab-titles in sequence 4 (last selected) through 1, tab-title and corresponding tab become hidden, and selection fallback is the previous tab
• closing an unselected tab-title does not deselect the current selection
• 2 additional cases: works with a randomized closing sequence with mixed selected and not