Create an irMinimum option

[cgewecke]

This should be a convenience setting for the IR solc config everyone was using in 0.8.5 and earlier. Using this is much more efficient than full viaIR and preferable if your project can compile like that.

We should also remove the deprecation language around the the solc config options in the docs - just describe them as "low-level" and discuss the efficiency trade-offs for the different settings.

irMinimum is what forge/solc are calling these settings, the name should be consistent across the tooling for intelligibility.

See discussion: OpenZeppelin/openzeppelin-contracts#5282 (comment)