Improve Logs panel UX

[Slach]

Open http://localhost:3000/d/VtsMXQl7z/test-logs-support
show log context doesn't work (work wrong in Grafana Labs plugin)

use Explore
filters in logs panel doesn't work

[Slach]

for context in logs
when trace_id is passed then just show

SELECT ... FROM $table WHERE $timeFilter AND trace_id=...

when only timestamp field passed
then
make two queries

1. detect timestamp boundaries for selected timestamp

SELECT min_timestamp, max_timestamp FROM (
  SELECT 
    timestamp, 
    FIRST_VALUE(timestamp) OVER (ORDER BY timestamp ROWS BETWEEN 10 PRECEDING AND CURRENT ROW) AS min_timestamp,
    LAST_VALUE(timestamp) OVER (ORDER BY timestamp ROWS BETWEEN CURRENT ROW AND 10 FOLLOWING) AS max_timestamp
  FROM $table 
  WHERE $timeFilter ORDER BY timestamp
) WHERE timestamp=XXXX

2. get whole data

SELECT ... FROM $table WHERE $timeFilter AND $timeStampField BETWEEN $min_timestamp AND $max_timestamp