jfr-datasource maximum HTTP file upload size should be configurable/overrideable

[andrewazores]

https://github.com/cryostatio/jfr-datasource/issues/83

The latest jfr-datasource image uses an updated Quarkus version, which limits the maximum HTTP body upload size to only 10M. This is too small for Cryostat's purposes. The jfr-datasource image should itself default to a more reasonable value, but the Operator should also know how to override this to a value that suits the actual Cryostat deployment scenario, ie scaling the maximum upload size based on the jfr-datasource container limits or how much storage may be attached to it.