Improve log limits UX : select log end & raised limit

[ddelemeny]

Issues #88 & #89 showcase bad UX of the current log query limit.

• Grafana's pagination components may fail up to v10.3, v10.4 should fix issues with the "older logs" button not working
  -> Won't fix, wait for next release, maybe document the issue ?

• Timestamp resolution matters, as grafana paginates on timestamp only and at the moment doesn't provide any hint about the data already fetched when issuing a page query. Too many records with the same timestamp will cause data to be skipped between pages. If this issue arises, using a finer timestamp resolution and raised query limits are the solution.
  -> Raise default query limits to 1000, partially fixes Make sure older logs can be explored #88 ?

• Chronological exploration of logs is a use case where the limit can cause frustration, because the current behavior only returns the log tail.
  -> Add a query setting to allow querying the log head (within the defined time range), fixes Add sort direction #89

Bonus refactoring

QueryEditorSpecialMetricRow and QueryEditorRow shared the same layout code, rename and refactor.

[ddelemeny]

Possible follow ups

• Configurable query defaults : I think it would be nice to allow users to tailor the default fragments used to initialize a query to their use-case. This would require substantial modifications to the query editor initialization, and a dedicated UX.
• Make the consequences of limits louder : find a way to alert the user of the possible log-skipping consequences of query limits and recommended workarounds