Tab completion gets in the way when constructing a query from the inside
out:
```
up| => |up => sum(|up)
```
At that point the language provider will not suggest anything.
In aggregation contexts using the alternate syntax form, labels will
precede metrics. A cursor at the label position cannot provide
meaningful suggestions unless a metric is specified. In the latter case,
no suggestions are presented at all.
Related: #13690
- changed `start()` to return promise on main language feature task
- promise resolves to list of secondary tasks
- speeds up time to interaction of metric selector
- lazy loading of certain metric selector and log label selector items
- loading indication of metric and log label selectors
this is a fix-up PR that cleans up Explore Logging after the recent
restructuring.
- log results need to be merged since query transactions have been
introduced
- logging DS has its own language provider, query field, and start page
(some of them based on prometheus components)
- added loader animation to log viewer
- removed logging logic from prometheus components
No label suggestions were being returned for multi-line aggregation
contexts because the parsed selector string does not see the full
context before a `by` or `without` clause.
This solution stitches together all text nodes that comprise the query
editor to ensure the selector has sufficient context to generate
suggestions.
Also, an additional workaround has been included to ensure range vector
syntax does not disrupt label suggestions in aggregation contexts.
Related: #12890
