ci: Merge MLIR Backend

[hameerabbasi]

What type of PR is this? (check all applicable)

• [ ] 💾 Refactor
• [ ] 🪄 Feature
• [ ] 🐞 Bug Fix
• [ ] 🔧 Optimization
• [ ] 📚 Documentation
• [x] 🧪 Test
• [x] 🛠️ Other

Checklist

• [x] Code follows style guide
• [x] Tests added
• [x] Documented the changes

---

Please explain your changes below.

• Merge MLIR backend tests to all others
• Add coverage testing for MLIR Backend
• Use micromamba-action.

[hameerabbasi]

Blocked due to scipy/scipy#21442, workaround in #757.

[codspeed-hq[bot]]

CodSpeed Performance Report

Merging #758 will improve performances by 84.76%

_{Comparing hameerabbasi:mlir-ci-merge (698dec2) with main (942c1e0)}

Summary

⚡ 1 improvements ✅ 243 untouched benchmarks

Benchmarks breakdown

	Benchmark	main	hameerabbasi:mlir-ci-merge	Change
⚡	test_index_fancy[side=100-rank=1-format='coo']	1,184 µs	640.8 µs	+84.76%

[mtsokol]

LGTM, but let's merge https://github.com/pydata/sparse/pull/757 first and see CI green.

[hameerabbasi]

LGTM, but let's merge #757 first and see CI green.

I cherry-picked the changes to not block this PR.