Codegen: update for position-only mapper exprs in pymbolic #1815

Job	Run time
Ruff	10s
basedpyright	2m 17s
Typos	6s
Documentation	1m 53s
Tests for downstream project pytential	36m 30s
Conda Pytest Symengine	36m 26s
Conda Pytest	32m 59s
Conda Examples	2m 18s
	1h 52m 39s

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