Sprites with parenthesis fail to rename without warning

[edwardrowe]

Report: https://forum.unity.com/threads/mulligan-renamer.532182/#post-7880896

Repro:

1. Create a spritesheet with a Sprite with a name that includes parenthesis. Ex: "Sprite_Jump(0)"
2. Add it to Bulk Renamer
3. Add a rule so to rename part of it. Ex: "Sprite" -> "Pic"
4. Rename
5. Notice the Sprite is not renamed

The issue is the regex to find these characters in the renamer. Since it doesn't escape the original name, it will fail to replace it in the meta as it won't be able to find it with the invalid regex as the old name.

The fix is to escape the original name.

[edwardrowe]

All special characters that we ban on Assets are actually allowed on Sprites. We can go ahead and remove all characters from the invalid list for Sprites.