feat(json-abi): add `AbiItem::json_type` (#797) #2137

Job	Run time
check no_std	49s
clippy	42s
features stable	2m 11s
docs	34s
features stable --all-targets	3m 33s
fmt	15s
features nightly	1m 32s
miri --no-default-features	4m 59s
features nightly --all-targets	3m 3s
miri	4m 38s
test ubuntu-latest stable --no-default-features	1m 23s
miri --all-features	7m 49s
wasm	36s
test ubuntu-latest stable	1m 22s
test ubuntu-latest nightly --no-default-features	54s
test ubuntu-latest nightly	53s
test ubuntu-latest 1.79 --no-default-features	41s
test ubuntu-latest 1.79	35s
test windows-latest stable --no-default-features	3m 36s
test windows-latest stable	3m 43s
test windows-latest nightly --no-default-features	1m 50s
test windows-latest nightly	1m 45s
test windows-latest 1.79 --no-default-features	1m 15s
test windows-latest 1.79	1m 50s
test ubuntu-latest 1.79 --features json	39s
test windows-latest 1.79 --features json	1m 55s
test ubuntu-latest nightly --all-features	1m 6s
test windows-latest nightly --all-features	2m 47s
ci success	2s
	56m 57s

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