refactor expression parsing and checksum checking #2109

Job	Run time
Docs - nightly toolchain (recent)	39s
Bench - nightly toolchain (recent)	2m 55s
Embedded	1m 9s
Docs - stable toolchain (recent)	34s
Format - nightly toolchain	18s
Integration tests - stable toolchain (26_0)	48s
Lint - nightly toolchain (recent)	45s
Integration tests - stable toolchain (25_2)	54s
Test - 1.63.0 toolchain (minimal)	25m 55s
Test - nightly toolchain (minimal)	14m 48s
Integration tests - stable toolchain (25_1)	59s
Test - 1.63.0 toolchain (recent)	27m 27s
Test - nightly toolchain (recent)	14m 37s
Integration tests - stable toolchain (25_0)	53s
Test - stable toolchain (minimal)	16m 1s
Integration tests - stable toolchain (24_2)	47s
Test - stable toolchain (recent)	16m 32s
Integration tests - stable toolchain (24_1)	51s
Integration tests - stable toolchain (24_0_1)	1m 1s
Integration tests - stable toolchain (23_2)	1m 1s
Integration tests - stable toolchain (23_1)	50s
Integration tests - stable toolchain (23_0)	52s
Integration tests - stable toolchain (22_1)	1m 5s
Integration tests - stable toolchain (22_0)	46s
Integration tests - stable toolchain (0_21_2)	1m 4s
Integration tests - stable toolchain (0_20_2)	53s
Integration tests - stable toolchain (0_19_1)	51s
Integration tests - stable toolchain (0_18_1)	52s
Integration tests - stable toolchain (0_17_1)	47s
	2h 16m 54s

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