Add support for Zilsd and Zcmlsd extensions

[lavanyajagan]

Description

Adding Support for Zilsd and Zcmlsd Extensions presented here:

Related Issues

The related PRs

• riscv-config support for the extension merged in dev PR
• riscv-isa-sim support for the extension available in master : commit id
• SAIL PR
• riscv-ctg PR
• riscv-isac PR
• Sample test env

This PR is depedent on the merging of the above PRs

Update to/for Ratified/Unratified Extensions or to framework

• Ratified
• Unratified
• Framework

List Extensions

The unratified spec document:
https://github.com/riscv/riscv-zilsd/blob/main/zilsd.adoc

Reference Model Used

• SAIL
• Spike
• Other - < SPECIFY HERE >

Mandatory Checklist:

• All tests are compliant with the test-format spec present in this repo ?
• Ran the new tests on RISCOF with SAIL/Spike as reference model successfully ?
• Ran the new tests on RISCOF in coverage mode
• Link to Google-Drive folder containing the new coverage reports (See this for more info): https://github.com/vyoma-systems/zilsd/coverage
• Link to PR in RISCV-ISAC from which the reports were generated : Add zilsd and zcmlsd instruction support riscv-software-src/riscv-isac#92
• Changelog entry created with a minor patch

Optional Checklist:

• RISCV-V CTG PR link if tests were generated using it : Add support for Zilsd and Zcmlsd extension riscv-software-src/riscv-ctg#117
• Were the tests hand-written/modified ? No
• Have you run these on any hard DUT model ? Please specify name and provide link if possible in the description
  We have run the tests on spike and sail supporting the extensions
  https://github.com/vyoma-systems/zilsd
• [] If you have modified arch_test.h Please provide a detailed description of the changes in the Description section above.

[lavanyajagan]

@jamesbeyond Could you review this PR. We have upstreamed to the latest dev structure