proto: Token encode refactors #5312

Job	Run time
test on illumos	6m 45s
test on freebsd	3m 48s
audit	24s
features (ubuntu-latest)	1h 22m 27s
lint	1m 2s
features (macos-latest)	24m 16s
msrv	1m 12s
features (windows-latest)	49m 48s
test (ubuntu-latest, stable)	1m 28s
test-android (x86_64-linux-android, x86_64, 26)	2m 53s
test (ubuntu-latest, beta)	1m 42s
test-android (x86_64-linux-android, x86_64, 25)	2m 38s
test (macos-latest, stable)	1m 8s
test-aws-lc-rs	1m 54s
test-android (i686-linux-android, x86, 26)	2m 57s
test (windows-latest, stable)	2m 54s
test on netbsd	5m 9s
test-android (i686-linux-android, x86, 25)	2m 28s
test on solaris	5m 20s
test wasm32-unknown-unknown	48s
	3h 21m 1s

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