Add separate table for byte and half loads and stores (far strings).
Add separate table for byte and half loads and stores (far strings).

- Byte and half are unlikely to be supported due to AMO width encoding.
- Constraint based the 2-bit width field of the AMO type width encoding
  (also frees aditional space in funct5).
- Need to consider how far strings work and whether these are needed.

Opcode             | Operands       | Notes
:----------        | :------------- | :---------
LB                 | flags rd,rs2(rs1)
LBU                | flags rd,rs2(rs1)
LH                 | flags rd,rs2(rs1)
LHU                | flags rd,rs2(rs1)
SB                 | flags rs3,rs2(rs1)
SH                 | flags rs3,rs2(rs1)

rv8-io/rv8,rv8-io/rv8,rv8-io/rv8