Introduce instr_reads_from_exact_reg

Feature request to create a new function, namely instr_reads_from_exact_reg, which returns whether an instruction reads directly and exactly from a given register.

For example: instr_reads_from_exact_reg(instr, xmm0) returns false if the instruction is vmov [m], zmm0, but returns true if the instruction is movdqa [m] xmm0.