Templatizes the AccumulatorUsage and OperandType for BytecodeNode creation and
BytecodeRegisterOptimizer::PrepareForBytecode. This allows the compiler to
statically know whether the bytecode being created accesses the accumulator
and what operand types need scaling, avoiding runtime checks in the code.

Also removes BytecodeNode::set_bytecode methods.

Review-Url: https://codereview.chromium.org/2542903003
Cr-Commit-Position: refs/heads/master@{#41706}