fix: tag filter ui for tasks

[Vafilor]

• Fixes an issue where tag filters did not do anything when the add button was clicked.
• Centralized TagFilter to it's own class
• Tasks can now be searched by both name and description in a single content field
• Remove allowing extra fields for filters. This was due to search, which was submitted, even though it shouldn't have been
• Remove html autocomplete from task input on task index page, as it can be annoying with the js autocomplete already there.

Closes #97