The ability to create custom tags

### Problem Description
I currently use tags to organize/categorize block and allow lists. I then apply different tags as needed to each client identifier. Currently, tag names are from a pick list and cannot be customized. So I have to randomly pick a tag name (that is named after a specific device or OS) and use that for a filter list that is for not related to that device or OS. This limits the ability to effectively use tags in a more expansive way.

### Proposed Solution
I believe tags are exceptionally useful to better normalize and manage filter list application for each client. For this type of use case, it would be easier to manage the tags if I can create additional custom tags and name them as I see fit to better denote what the tag is for. This can be done from the UI or the config file directly.

### Alternatives Considered
Picking any tag name not related to filter list purpose and simply remembering what this particular tag is actually used for. This works with a little note keeping but it is still limiting and disorganized.

### Additional Information
None