Core Execute: XCrypto and Bitmanip functionality

[ben-marshall]

Functional unit modification and additions for XCrypto and Bitmanip.

• [x] New functional unit for SHA256/SHA512/SHA3
• [x] New functional unit for AES
• [x] New multi-precision functional unit.
• [x] New RNG functional unit.
• [x] Swap ALU functional unit for packed implementation from scarv/xcrypto-rtl
  • [x] Add funnel shift implementation.
  • [x] Add cmov implementation.
  • [x] Add xc.lut and xc.bop implementation.
• [x] FU result multiplexing for next pipeline stage.

[ben-marshall]

Done