Combine glass chair and transparent seat

BUR #63199 has been approved by @evazion.

create alias glass_chair -> transparent_seat

Both tags are essentially the same.

The wiki for glass chair even states "Do not use", but some still use it. transparent_Seat is more widely used, so it should become the new standard. transparent_* in also used in many other tags.

Alias instead of rename because I think "glass chair" is a reasonable description if someone doesn't know of the other tag.

imo we need a tag for post #4632462 and a separate tag for post #10598981

post #9897434 for example should be a wooden school chair but it's transparent

we also have against fourth wall which is a similar concept

or i guess we could put both in the same tag and just tag everything from below or worm's eye view?

The bulk update request #63199 (forum #456676) has been approved by @evazion.