Ignore BX_INSERTED_OPCODE in BeforeExecutionHook

[0vercl0k]

This PR fixes the issue that happened in #45 - basically bx inserts a 'special' instruction (w/o changing its address) which gets treated like a normal instruction and so the before_execution hook gets invoked on it as well but right after, another before_execution gets dispatched on the 'real' instruction. This triggered RIP traces to generate traces that looked like:

0x7ffbd6641ff9
0x7ffbd6641ff9
0x7ffbd6642001
0x7ffbd6642001

Instead of:

0x7ffbd6641ff9
0x7ffbd6642001

This behavior also meant that it triggered the code that generates the Tenet deltas to generate an empty line which the Tenet plugin doesn't like :).

On top of the above the PR does a few other things:

• Fix a bug in Tenet where state wasn't reset in between runs,
• Fix a bug in Tenet where the last delta could be empty which generated two empty lines at the end of the file,
• Rename ShowRegisters to PrintRegisters, updated the bx dependencies to the 2.7 version, CI uses clang13, added Backend::Rsi/Backend::Rdi, remove the virtual keyword from the hook functions in the bxcpu backend.