Add HasHarnessInstantiators into MultiHarnessBinder

[abejgonzalez]

In general, users should be able to generate arb. RTL in the harness and connect up any clock they want to it (for example to connect up a queue between IOs, debugging loggers, etc). This is supported with current HarnessBinders but not with MultiHarnessBinders specifically because the Multi* version doesn't have access to th: HasHarnessInstantiators. This adds this back to the MultiHarnessBinder when it was dropped on the PortAPI changes.

Related PRs / Issues:

Type of change:

• Bug fix
• New feature
• Other enhancement

Impact:

• RTL change
• Software change (RISC-V software)
• Build system change
• Other

Contributor Checklist:

• Did you set main as the base branch?
• Is this PR's title suitable for inclusion in the changelog and have you added a changelog:<topic> label?
• Did you state the type-of-change/impact?
• Did you delete any extraneous prints/debugging code?
• Did you mark the PR with a changelog: label?
• (If applicable) Did you update the conda .conda-lock.yml file if you updated the conda requirements file?
• (If applicable) Did you add documentation for the feature?
• (If applicable) Did you add a test demonstrating the PR?

• (If applicable) Did you mark the PR as Please Backport?

[abejgonzalez]

Ready for review.