replace pyrsistent.PMap, immutables.Map, immutabledict with constantdict #3448

Job	Run time
Pylint	1m 40s
Conda Pytest with Intel CL	3m 19s
Conda Pytest (ubuntu-latest)	3m 51s
Conda Pytest without arg check	3m 46s
Conda Pytest (macos-latest)	3m 40s
Conda Pytest Twice (for cache behavior)	5m 0s
Ruff	5s
Typos	4s
Documentation	1m 27s
Tests for downstream project Firedrake	2m 37s
Tests for downstream project arraycontext	2m 33s
Conda Examples	1m 47s
Tests for downstream project meshmode	12m 46s
Validate CITATION.cff	10s
Tests for downstream project grudge	10m 6s
Tests for downstream project pytential	40m 10s
Tests for downstream project pytato	5m 58s
Mypy	1m 27s
	1h 40m 26s

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