Before, the `dict "ctx" ...` map is used to pass data between templates.
Now, more and more templates need to use real Go context:
* #22962
* #23092
`ctx` is a Go concept for `Context`, misusing it may cause problems, and
it makes it difficult to review or refactor.
This PR contains 2 major changes:
* In the top scope of a template, the `$` is the same as the `.`, so the
old labels_sidebar's `root` is the `ctx`. So this `ctx` could just be
removed.
bd7f218dce
* Rename all other `ctx` to `ctxData`, and it perfectly matches how it
comes from backend: `"ctxData": ctx.Data`.
7c01260e1d
From now on, there is no `ctx` in templates. There are only:
* `ctxData` for passing data
* `Context` for Go context
ce73492d6f