feat: add variable gas feature

[howydev]

userOp.signature format changes from:

1. k signatures
2. to: upperLimitPreVerificationGas | upperLimitMaxFeePerGas | upperLimitMaxPriorityFeePerGas | k signatures

If the upperLimitPreVerificationGas, upperLimitMaxFeePerGas or upperLimitMaxPriorityFeePerGas differs from preVerificationGas, userop.maxFeePerGas or userop.maxPriorityFeePerGas, we expect at least 1 sig on the actual gas values used in the userop. This verification prevents a bundler or front runner manually running entryPoint.handleOps with any gas values

We use the v value to switch between signatures on the userOpHashes with upper limit gas values or the actual gas values:

1. v = 0 refers to contract sigs on upper limit values
2. v = 32 refers to contract sigs on actual values
3. v = 27/28 refers to EOA sigs on upper limit values
4. v = 59/60 refers to EOA sigs on actual values

notes:

1. requires via-ir to compile (else stack too deep)
2. dummy sig should use variable gas by default. else it can potentially be underpriced on the order of a few hundred to thousands of gas