Add some mpoly context util functions #979

Job	Run time
Test docs (build and doctest)	4m 36s
Build sdist	2m 57s
Build wheels for ubuntu-20.04	14m 7s
Build on ubuntu-24.04	2m 1s
Build wheels for windows-2019	29m 8s
Test coverage setuptools build	4m 56s
Build wheels for macos-13	18m 20s
Test flint main	4m 38s
Build wheels for macos-14	9m 17s
Test flint v3.0.0	5m 0s
Free-threaded 3.13-dev on ubuntu-24.04	5m 12s
Test old Cython/meson-python	1m 57s
Test flint v3.0.1	4m 57s
Test flint v3.1.0	4m 39s
Test flint v3.1.1	4m 38s
Test SymPy 1.13.1	18m 13s
Test flint v3.1.2	4m 36s
Test 3.10 wheel on ubuntu-20.04	12s
Publish to PyPI	0s
Test 3.11 wheel on ubuntu-20.04	12s
Test 3.12 wheel on ubuntu-20.04	8s
Test 3.13-dev wheel on ubuntu-20.04	23s
Test pypy3.10 wheel on ubuntu-20.04	20s
Test 3.10 wheel on windows-2019	20s
Test 3.11 wheel on windows-2019	15s
Test 3.12 wheel on windows-2019	21s
Test 3.13-dev wheel on windows-2019	1m 8s
Test pypy3.10 wheel on windows-2019	21s
Test 3.10 wheel on macos-13	11s
Test 3.11 wheel on macos-13	12s
Test 3.12 wheel on macos-13	13s
Test 3.13-dev wheel on macos-13	54s
Test pypy3.10 wheel on macos-13	17s
Test 3.10 wheel on macos-14	8s
Test 3.11 wheel on macos-14	10s
Test 3.12 wheel on macos-14	9s
Test 3.13-dev wheel on macos-14	34s
Test pypy3.10 wheel on macos-14	19s
Publish GitHub release	0s
	2h 25m 59s

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