Calculate SignVerify region number of rows at runtime

[ed255]

In https://github.com/privacy-scaling-explorations/zkevm-circuits/pull/994 we introduced methods for each circuit to report the minimum number of rows required. The SignVerify circuit uses halo2wrong, making the number of rows required opaque. The number of rows required were obtained by patching halo2 locally and then hardcoded: https://github.com/privacy-scaling-explorations/zkevm-circuits/blob/8f934de0cffe37bc645d064eff00d2ebc212a93b/zkevm-circuits/src/tx_circuit/sign_verify.rs#L76-L87

Once https://github.com/privacy-scaling-explorations/halo2/issues/112 is ready, we should use the new API instead to get those numbers.

[davidnevadoc]

I reopned the issue because I think with the current changes it is not possible to retrieve this info in configure time.

[davidnevadoc]

Blocked by issue https://github.com/privacy-scaling-explorations/halo2/issues/112