[Task] Fine-grained replacement parameter for Start Recording Mutator

[tthvo]

Describe the feature

I think the best thing to do here is actually just ignore the request on any targets that already have such a recording running, since starting a new parallel active recording in the same running state doesn't actually capture any additional data. If the recording doesn't exist, it should be created and started. If it exists but has been stopped, it should be restarted. If it is already running just do nothing.

This I think probably can and should be done server-side.

https://github.com/cryostatio/cryostat/blob/2b0cd5adacf8f928f8666f36663b0a5b31e0e76b/src/main/java/io/cryostat/net/web/http/api/v2/graph/StartRecordingOnTargetMutator.java#L181

https://github.com/cryostatio/cryostat/blob/2b0cd5adacf8f928f8666f36663b0a5b31e0e76b/src/main/java/io/cryostat/recordings/RecordingTargetHelper.java#L157

Currently, when requesting to start a recording, the client can use a query parameter or GraphQL argument restart to ask the server to close and re-open any recordings that already exist with the same name as in the new request. If this parameter is not provided or is false then the server will either create the new recording or will fail with an exception. If the parameter is true then the server will either create the new recording, or will stop the existing recording and start a new one with the other request parameters (event template, maxAge/maxSize settings, etc.).

I think this behaviour makes sense to retain, and it is already part of published API so it would be nice to be able to enhance this while keeping the same request format. I would propose that the query parameter ?restart=[true|false] be kept but documented as deprecated, and a new replacement like ?replace=[always,stopped,never] introduced. ?replace=always would behave the same as ?restart=true, ?replace=never would behave the same as ?restart=false, and ?replace=stopped would implement the quoted behaviour. If replace is not specified then it should behave like ?replace=never, so that this also maintains consistency and compatibility with the existing ?restart=false default behaviour.

Originally posted by @andrewazores in cryostatio/cryostat-web#1035 (comment)