der: add `GeneralString` variant to `Tag` (#1512) #2434

Job	Run time
build (1.65.0, thumbv7em-none-eabi)	1m 49s
build (1.65.0, wasm32-unknown-unknown)	1m 53s
test (1.65.0)	2m 21s
build (stable, thumbv7em-none-eabi)	20s
test (stable)	44s
build (stable, wasm32-unknown-unknown)	12s
minimal-versions / minimal-versions	40s
	7m 59s

Provide feedback