Add topdown test

[mattweingarten]

Add BOOM top-down microarchitecture benchmark and HPM event evaluation

Adds a benchmark for evaluating BOOM top-down microarchitecture analysis counters and validating the new HPM event infrastructure. The benchmark exercises frontend-bound, backend-bound, retiring, and bad-speculation behaviors.

Related PRs / Issues:

• Related: BOOM HPM event infrastructure and topdown support.

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?

CI Help:
Add the following labels to modify the CI for a set of features.
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• ci:fpga-deploy - Run FPGA-based E2E testing
• ci:local-fpga-buildbitstream-deploy - Build local FPGA bitstreams for platforms that are released
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