[Compiler+VM PoC] Refactor instruction encoding/decoding

[turbolent]

Description

• Introduce an Instruction interface and define concrete types for all instructions
• Refactor the encoding functions to use the instruction type as an input (receiver)
• Refactor the decoding functions to output the instruction types
• Refactor the printing function into separate methods on the instruction types
• Refactor the compiler to emit instruction types
• Add a code gen that gathers the emitted instructions as-is, without encoding them to bytecode

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• Targeted PR against master branch
• Linked to Github issue with discussion and accepted design OR link to spec that describes this work
• Code follows the standards mentioned here
• Updated relevant documentation
• Re-reviewed Files changed in the Github PR explorer
• Added appropriate labels

[SupunS]

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