Feat: Add Ability to Enable/Disable Custom Commands and Custom Replacements

[pjkaufman]

Fixes #1223 #1098

There have been several requests to allow custom commands and custom replacements to be able to be enabled and disabled.

Changes Made:

• Added tests to make sure that disabled custom replacement/command is not run
• Updated the logic for checking for custom commands to see if there are any non-disabled custom commands
• Swapped the x/cross icon to be the trash icon to be more consistent with obsidian
• Added logic in the onload function to try to add the enabled property if it is missing for custom commands/replacements