Remove some old plugins

[ret2libc]

WDYT?

[wargio]

can we move these into a disabled folder ?

[notxvilka]

Keystone could be removed, rz-svd (after it's integrated into the Rizin), libmc7 still should be useful. KVX, ZPU, and Jaguar - no strong opinion.

[ret2libc]

@notxvilka rz-svd was last touched 3/5 years ago. Does it even work? Is it even used? If it's not building, there's no reason to keep it in the plugins because then people will see the plugin but they won't be able to use it.

libmc7 was last updated last year for rizin v0.7.3. I think it won't be anymore given the various changes since then.

The others are all part of rizin-extras, which is abandoned at this point.