Migration fix with improved CLI and docs.

[pawks]

• Changed CI script from gitlab to github actions
• Removing hosted cgf files
• Removing hosted riscv-test-suite
• Removing hosted database.yaml
• Updated report to capture the version of the riscv-arch-test suite used during run
• Added new cli - 'arch-test' to automatically clone, update and maintain the riscv-arch-test repo
• Using annotated tags for CI releases
• suite and env are now required cli args
• updated docs
  • added new sections on commands and inputs.
  • Revised the installation and riscv-arch-test sections.
  • Fixed testlist and dbgen usage and formats
  • Cleaned up examples.
  • Removed testformat spec.
  • Removed section on adding new tests.
  • Adding new doc on available PLUGINS for RISCOF.
  • Fixed links for new repo transition