Add public interface for adding continuation types to `CoreTypeEncoder` #5407

Job	Run time
Test the C API (ubuntu-latest)	43s
Test (ubuntu-latest, stable)	2m 34s
Test the C API (macos-latest)	48s
Test with extra Cargo features	1m 45s
Test (ubuntu-latest, beta)	2m 35s
Test the C API (windows-latest)	3m 33s
Test (ubuntu-latest, nightly)	2m 24s
Test (macos-latest, stable)	2m 8s
Test (windows-latest, stable)	6m 6s
Build wasm-tools (x86_64-linux, ubuntu-latest)	2m 35s
Test (ubuntu-latest, msrv, --exclude fuzz-stats --exclude wit-component --exclude wasm-mutate-stats)	2m 12s
Test libdl.so	1m 7s
Build wasm-tools (x86_64-macos, macos-latest, x86_64-apple-darwin)	2m 0s
Test (no-hash-maps)	2m 43s
Test (ubuntu-latest, nightly-2024-07-12)	2m 28s
Build wasm-tools (aarch64-macos, macos-latest, aarch64-apple-darwin)	1m 58s
Test (ubuntu-latest, stable, 1)	2m 30s
Build wasm-tools (x86_64-windows, windows-latest)	5m 56s
Test on WebAssembly	3m 31s
Build wasm-tools (aarch64-linux, ubuntu-latest, aarch64-unknown-linux-gnu)	2m 54s
Build wasm-tools (wasm32-wasip1, ubuntu-latest, wasm32-wasip1)	1m 59s
check	2m 54s
clippy	1m 19s
doc	1m 47s
Fuzz	2m 12s
Check generated files are up-to-date	57s
Rustfmt	9s
verify-publish	2m 29s
Record the result of testing and building steps	1s
maybe-trigger-tag	0s
	1h 6m 17s

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