Add a parameter `replace` to RPC `/injection/operation(s)` to specify if an existing operation(s) should be replaced or not

This issue is a follow up of !4115 (merged) / #2292 (closed)

Currently, if a user injects an operation from the same manager with enough fees, while there is already an applied operation of the same manager (and with the same counter) in the mempool, the first operation is silently replaced.

We may want to add a boolean parameter replace to operation(s) injection RPCs, to only enable the replacement if the flag is set to true.