Disabled IndexEditorProvider

[Davide Giannella <da...@apache.org>]

Hello Team,

during this first year with Oak 1.0.x we took the habit to use the
`disabled` has index type when we wanted to disable (temporary or not)
an index.

It works, but it could lead to errors that are difficult to investigate
later on if/when re-enabled. For example the index will be out of sync
and most probably need a reindex.

My idea, for the 1.4 timeframe, is to have a
`DisabledIndexEditorProvider` which will play in case of
oak:QueryIndexDefinition.type=disabled. It will simply track a WARN
message in the log every X updates (let's say 5000?) per JVM. In this
way when investigating potential issues with indexes not playing nicely
we could easier spot the use case when the index was disabled and then
re-enabled.

Thoughts? If you think it can be useful I will file a ticket for not
loosing the idea.

Cheers
-- Davide