Add unratified Zcmop extension

[ved-rivos]

Description

Provide a detailed description of the changes performed by the PR.
Add support for Zcmop extension.

Related Issues

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Update to/for Ratified/Unratified Extensions

• Ratified
• [X ] Unratified

List Extensions

List the extensions that your PR affects. In case of unratified extensions, please provide a link to the spec draft that was referred to make this PR.

https://github.com/riscv/riscv-isa-manual/blob/main/src/zimop.adoc

Mandatory Checklist:

• [ X] Make sure you have updated the versions in setup.cfg and riscv_config/__init__.py. Refer to CONTRIBUTING.rst file for further information.
• [ X] Make sure to have created a suitable entry in the CHANGELOG.md.