[Feature] Tag tree for Nested Tags

[coscosname]

Is your feature request related to a problem? Please describe.
When viewing new nested tags, you don't know what our tag structure looks like which can make it difficult to edit.

Describe the solution you'd like
I propose to add "tag tree" as another display mode on the /tags subpage and for the currently selected tag on the /tags/tag_id subpage.

An example of a tag tree /tags

.
├── tag1
│   ├── tag1.1
│   ├── tag1.2
│   │   └── tag1.2.1
│   │       └── tag1.2.1.1
│   └── tag1.3
├── tag2
│   ├── tag2.1
│   │   ├── tag2.1.1
│   │   └── tag2.1.2
│   └── tag2.2
└── tag3

Example of tag tree for /tags/tag2.1

.
├── tag2.1.1
└── tag2.1.2