Support creating detached memo for nested isolated deepcopy calls

[Bobronium]

No description provided.

[codspeed-hq]

Merging this PR will degrade performance by 23.27%

❌ 1 (👁 1) regressed benchmark
✅ 357 untouched benchmarks

Performance Changes

	Benchmark	BASE	HEAD	Efficiency
👁	test_individual_cases[copium-cpython:91610:repeating_atomic]	22.8 µs	29.7 µs	-23.27%

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_{Comparing support-creating-detached-memo (4c3cae9) with main (b3d838c)}