System & server health check (independent of GUI & nagios)

As a VESUVIO instrument scientist I want to know if either my block or instrument archiver is not running so that I can take remedial action.

This information in cycle is alerted on by Nagios but the instrument scientist would like to know.

Preferably something similar to the error users see when the block server is not up.

NB Check should be that it is healthy not the process is around.

## Acceptance Criteria
1. Finish defining the acceptance criteria with what we expect
2. Consider the distribution methods
3. Nagios may be enough on it's own

## Notes

Per discussion in comments, this would ideally be a check independent of the GUI, which would then be usable by other components (e.g. potentially the web dashboard, genie_python). We may wish to internally re-use some of the nagios infrastructure, but this should be ultimately scientist-facing which nagios is not.

まず、既存の Nagios checks と、block server が利用できない場合に表示される GUI メッセージを確認し、次に web dashboard または genie_python で check を再利用できるか検討してください。“healthy” が何を意味するか、また Nagios だけで十分かどうかを含め、受け入れ基準と配布方法を定義してください。

索引モデルが issue の本文から書いたものです。