Preliminary OS support

[CKeilbar]

This PR includes initial changes that will be necessary to run an operating system on CVA5 in the future.
In addition to clarity and QoL changes, this primarily includes:

• Full support for the 20240411 RISC-V privileged architecture (previously a draft spec from ~2017-2019 was mostly supported)
• New separate TLB's for instructions and data
• Support for Sv32 virtual memory
• Many significant bugfixes for interrupt and exception handling (can close Interrupts can lead to MEPC inconsistent with register state / actually retired operations or pointing to entirely illegal instructions #19)
• Support for the RISC-V atomic extension (can close State of AMO support #21)
• Simulation support for the latest version of Verilator