Support deleting param for preconnected sessions

Although we can pass arbitrary pointers to setup preconnected clients,
the lifetime isn't clear and it's very easy to make UAF bugs.

To prevent UAF, an additional function can be passed to delete param
when param is no longer required, effectively transferring the ownership
of param to RPC session.

Bug: 398890208
Test: atest MicrodroidTests
Change-Id: I1a1c149a56876f56fba81b89cdc90ee372d2d7fe