Handle branches that occur in the middle of a block about ibresolver

[ayrtonm]

Since arm32 can have conditional indirect branches (e.g. ldreq PC, Rn) we shouldn't assume that these branches only occur at the end of a translation block. Fortunately it seems that callbacks registered for instructions executed work without singlestep mode so handling the ignored callsites won't require a lot of changes.

To handle these indirect branches we should register an insn exec callback for the branch and another for the following instruction. The first callback will set indirect_taken to the branch address like at the end of indirect_block_exec_handler and the second callback will set it to nullopt in case the branch is not taken. If the branch is taken, the default callback for executing a block will mark where the branch's destination.