Migrate to latest RISC-V Architecture Test

[jserv]

Recently, RISC-V Architecture Test SIG refines the build system and introduces RISC-V Compatibility Framework (RISCOF) which enables testing of a RISC-V target (hard or soft implementations) against a standard RISC-V golden reference model using a suite of RISC-V architectural assembly tests. It implies dramatical incompatibility, and we would stick to the old framework based on GNU make at the moment. Quote from riscv-arch-test:

The older 2.x version of the framework (based on Makefiles) can be found in a separate branch : old-framework-2.x. This branch is officially no longer supported and all changes must occur on the main branch.

In order to synchronize with latest RISC-V Architecture Tests, we shall migrate.