fix: allow commas and semicolons between fields in constant messages #2063

Job	Run time
linux beta (default features)	7m 2s
Check sync-readme	1m 31s
linux stable (default features)	7m 44s
linux nightly (all features)	6m 38s
linux stable (with-bytes)	9m 10s
mega-linter	2m 9s
Miri test	42s
CI self-check	6s
rustfmt check	5m 48s
windows stable (default features)	3m 34s
	44m 24s

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