Add Support for CSR Side Effects

[kathlenemagnus-mips]

For some CSRs, writing a new value can have side effects on the program state. For example, writing to the MISA CSR can change which extensions are enabled which needs to be communicated to Atlas.

By utilizing the ActionGroup design, the CSR side effects can be defined as Actions which are only inserted into instructions that update those CSRs. CSR side effect Actions should be maintained by a new class so that they can be accessed by AtlasCoSim in the future.