feat: add fixed size variant of bytes as a separate `FixedBytes` type #2704

Job	Run time
check-change-log-fragment	11s
check-python	1m 25s
tests (1, not localnet)	2m 19s
summarize-size	39s
tests (2, localnet)	2m 7s
tests (2, not localnet)	1m 51s
tests (1, localnet)	2m 35s
tests-windows (2, not localnet)	2m 46s
tests-windows (1, not localnet)	3m 26s
compile-all (-O0)	2m 39s
compile-all-windows (-O0)	4m 18s
compile-all-windows (-O1)	4m 11s
compile-all (-O2)	2m 49s
Run PuyaPy on Windows via cmd	56s
compile-all-windows (-O2)	4m 22s
Build and test binaries / Generate smoke-test inputs	22s
Build and test binaries / Build Linux binaries (ubuntu-22.04, x64)	1m 5s
Run PuyaPy on Windows via pwsh	1m 4s
Run PuyaPy on Windows via bash	57s
Build and test binaries / Build Linux binaries (ubuntu-22.04-arm, arm64)	1m 8s
Build and test binaries / Build macOS binaries (macos-14, arm64)	1m 4s
Build and test binaries / Build Windows binaries (windows-latest, x64)	3m 28s
Build and test binaries / Build macOS binaries (macos-13, x64)	2m 10s
compile-all (-O1)	2m 47s
Build and test binaries / Smoke test ${{ matrix.distro.name }} ${{ matrix.arch.name }}	0s
coverage	22s
Build and test binaries / Smoke test ubuntu-22.04-arm	6s
Build and test binaries / Smoke test ubuntu-22.04	9s
Build and test binaries / Smoke test windows-latest	10s
Build and test binaries / Smoke test macos-13	19s
Build and test binaries / Smoke test macos-14	10s
	51m 55s

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