Allow MyXQL to specify `:prepare` per operation. #1739

Job	Run time
unittest (1.17.2, 25.0.4)	14s
postgres integration test (1.11.4-erlang-23.3.4.9-alpine-3.16.9, 16.2-alpine, 1)	1m 47s
unittest (1.17.2, 27.0.1, lint)	16s
mysql integration test (1.11.4-erlang-23.3.4.9-alpine-3.16.9, 5.7)	2m 6s
postgres integration test (1.11.4-erlang-23.3.4.9-alpine-3.16.9, 11.11-alpine, 1)	1m 44s
mssql integration test (1.11.4-erlang-23.3.4.9-alpine-3.16.9, 2017)	2m 20s
mysql integration test (1.11.4-erlang-23.3.4.9-alpine-3.16.9, 8.0)	2m 10s
postgres integration test (1.11.4-erlang-23.3.4.9-alpine-3.16.9, 9.6-alpine, 1)	1m 47s
mssql integration test (1.11.4-erlang-23.3.4.9-alpine-3.16.9, 2019)	2m 8s
postgres integration test (1.11.4-erlang-23.3.4.9-alpine-3.16.9, 9.5-alpine, 1)	1m 46s
postgres integration test (1.11.4-erlang-23.3.4.9-alpine-3.16.9, 16.2-alpine, 4)	1m 46s
	18m 4s

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