[http-client-python] Apply `includeRootSlashOption` to operation level

[tadelesh]

Currently, includeRootSlashOption is applied to client level, we want to also apply it to operation level, and operation level could override the client level setting.

[timotheeguerin]

Same as #9933 can we get clarity on why this is needed at the client level

[l0lawrence]

Background context -- azure-storage-blob there is currently one client, but multiple interfaces for the "service" interface storage blob requires that the operations have a '/' before the route '_url = /?comp=foo', for all the other storage blob operations (interface pageBlob, appendBlob etc.) we do not want to have a '/' before the route '_url=?comp=pages'. I was looking for a way to remove the slash from all operations except for the service ones