Add Candid assist feature in candid_parser

[chenyan-dfinity]

A textual version of Candid UI: given a type, construct candid value in terminal with interactive dialogue.

[github-actions]

Benchmark for 138df31

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Test	Base	PR	%
Blob/&str	630.5±88.12µs	632.2±97.74µs	+0.27%
Blob/ByteBuf	368.0±88.82µs	373.1±90.33µs	+1.39%
Blob/Bytes	400.5±76.24µs	403.6±77.75µs	+0.77%
Blob/String	653.6±252.35µs	663.7±261.08µs	+1.55%
Collections/vec (text, nat)	50.4±1.62ms	51.1±1.98ms	+1.39%
Collections/vec int	23.6±0.13ms	23.0±0.08ms	-2.54%
Collections/vec int64	15.6±0.76ms	15.2±0.16ms	-2.56%
Collections/vec nat8	11.5±0.04ms	11.5±0.05ms	0.00%
option list/1024	945.4±8.77µs	956.9±13.10µs	+1.22%
profiles/1024	1743.9±33.17µs	1766.6±74.84µs	+1.30%
variant list/1024	804.9±14.99µs	811.9±25.82µs	+0.87%

[github-actions]

Benchmark for 8092c0c

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Test	Base	PR	%
Blob/&str	618.5±109.98µs	582.7±88.16µs	-5.79%
Blob/ByteBuf	344.0±92.89µs	340.6±89.21µs	-0.99%
Blob/Bytes	379.1±62.76µs	352.8±56.80µs	-6.94%
Blob/String	331.5±134.15µs	323.2±122.42µs	-2.50%
Collections/vec (text, nat)	48.0±0.69ms	47.3±0.37ms	-1.46%
Collections/vec int	23.3±0.07ms	23.6±0.73ms	+1.29%
Collections/vec int64	15.2±0.04ms	14.5±0.09ms	-4.61%
Collections/vec nat8	10.9±0.04ms	11.1±0.02ms	+1.83%
option list/1024	951.6±9.93µs	957.9±9.96µs	+0.66%
profiles/1024	1733.5±16.71µs	1738.5±28.69µs	+0.29%
variant list/1024	788.7±12.36µs	808.8±9.90µs	+2.55%

[github-actions]

Benchmark for 7665251

Click to view benchmark

Test	Base	PR	%
Blob/&str	616.8±105.27µs	589.1±98.72µs	-4.49%
Blob/ByteBuf	352.0±87.50µs	353.6±91.31µs	+0.45%
Blob/Bytes	384.3±62.42µs	357.9±61.46µs	-6.87%
Blob/String	333.9±138.20µs	366.2±124.43µs	+9.67%
Collections/vec (text, nat)	50.7±1.51ms	49.6±1.32ms	-2.17%
Collections/vec int	23.5±0.09ms	23.6±0.66ms	+0.43%
Collections/vec int64	14.7±0.06ms	15.5±0.07ms	+5.44%
Collections/vec nat8	10.9±0.04ms	11.1±0.05ms	+1.83%
option list/1024	939.4±9.48µs	958.9±8.79µs	+2.08%
profiles/1024	1730.2±37.19µs	1788.7±20.99µs	+3.38%
variant list/1024	787.6±10.38µs	804.1±11.61µs	+2.09%