Add Support for Vector Reduction Instructions

[kathlenemagnus-mips]

Add vector sequencer and execution support for the vector reduction instructions. At least 1 test should be added with an instruction from each category to verify proper sequencing.

• Vector Reduction Operations: Vector Single-Width Integer Reduction Instructions
• Vector Reduction Operations: Vector Widening Integer Reduction Instructions
• Vector Reduction Operations: Vector Single-Width Floating-Point Reduction Instructions
• Vector Reduction Operations: Vector Widening Floating-Point Reduction Instructions