enable v8 fast api across workerd

[anonrig]

There is no need to hide v8 fast api behind an autogate at the moment. We can roll it to the RoW.

According to local run of tests before and after these changes, **here's the top 50 improved test durations** and their percentage of improvement (according to claude)

Test Name	Run 1	Run 2	Difference	% Change
//src/workerd/api:api-rtti-test@all-autogates-enabled	0.4s	0.1s	-0.3s	-75.0%
//src/workerd/api:crypto/aes-test	0.4s	0.1s	-0.3s	-75.0%
//src/workerd/api:crypto/impl-test@all-autogates-enabled	0.4s	0.1s	-0.3s	-75.0%
//src/workerd/api:form-data-memory-test	0.4s	0.1s	-0.3s	-75.0%
//src/workerd/api:headers-test@all-autogates-enabled	0.4s	0.1s	-0.3s	-75.0%
//src/workerd/io:compatibility-date-test@all-autogates-enabled	0.4s	0.1s	-0.3s	-75.0%
//src/workerd/io:worker-fs-test	0.4s	0.1s	-0.3s	-75.0%
//src/workerd/api:basics-test	0.3s	0.1s	-0.2s	-66.7%
//src/workerd/api:basics-test@all-autogates-enabled	0.3s	0.1s	-0.2s	-66.7%
//src/workerd/api:crypto/impl-test	0.3s	0.1s	-0.2s	-66.7%
//src/workerd/api:form-data-memory-test@all-autogates-enabled	0.3s	0.1s	-0.2s	-66.7%
//src/workerd/api:pyodide/pyodide-test@all-autogates-enabled	0.3s	0.1s	-0.2s	-66.7%
//src/workerd/api:util-test	0.3s	0.1s	-0.2s	-66.7%
//src/rust/gen-compile-cache:gen-compile-cache_test	0.2s	0.1s	-0.1s	-50.0%
//src/workerd/api:actor-state-iocontext-test@all-autogates-enabled	0.4s	0.2s	-0.2s	-50.0%
//src/workerd/api:api-rtti-test	0.2s	0.1s	-0.1s	-50.0%
//src/workerd/api:headers-test	0.2s	0.1s	-0.1s	-50.0%
//src/workerd/api:pyodide/pyodide-test	0.2s	0.1s	-0.1s	-50.0%
//src/workerd/api:streams/queue-test	0.6s	0.3s	-0.3s	-50.0%
//src/workerd/api:streams/queue-test@all-autogates-enabled	0.6s	0.3s	-0.3s	-50.0%
//src/workerd/api:tests/error-in-error-event-test	0.4s	0.2s	-0.2s	-50.0%
//src/workerd/api:util-test@all-autogates-enabled	0.2s	0.1s	-0.1s	-50.0%
//src/workerd/io:compatibility-date-test	0.2s	0.1s	-0.1s	-50.0%
//src/workerd/io:promise-wrapper-test	0.6s	0.3s	-0.3s	-50.0%
//src/workerd/io:promise-wrapper-test@all-autogates-enabled	0.6s	0.3s	-0.3s	-50.0%
//src/workerd/io:worker-fs-test@all-autogates-enabled	0.2s	0.1s	-0.1s	-50.0%
//src/workerd/jsg:promise-test@all-autogates-enabled	0.4s	0.2s	-0.2s	-50.0%
//src/workerd/jsg:rtti-test	0.2s	0.1s	-0.1s	-50.0%
//src/workerd/jsg:setup-test@all-autogates-enabled	0.6s	0.3s	-0.3s	-50.0%
//src/workerd/jsg:struct-test@all-autogates-enabled	0.4s	0.2s	-0.2s	-50.0%
//src/workerd/tests:test-fixture-test	0.9s	0.5s	-0.4s	-44.4%
//src/workerd/tests:test-fixture-test@all-autogates-enabled	0.9s	0.5s	-0.4s	-44.4%
//src/workerd/api/node:buffer-test	2.0s	1.1s	-0.9s	-45.0%
//src/workerd/api/node:buffer-test@all-autogates-enabled	2.0s	1.1s	-0.9s	-45.0%
//src/workerd/api/node:tests/crypto_pbkdf2-test	0.7s	0.4s	-0.3s	-42.9%
//src/workerd/api:streams/streams-test	0.7s	0.4s	-0.3s	-42.9%
//src/workerd/jsg:iterator-test@all-autogates-enabled	0.5s	0.3s	-0.2s	-40.0%
//src/workerd/jsg:struct-test	0.5s	0.3s	-0.2s	-40.0%
//src/workerd/api:data-url-test@all-autogates-enabled	0.3s	0.2s	-0.1s	-33.3%
//src/workerd/api:streams/internal-test	0.4s	0.3s	-0.1s	-25.0%
//src/workerd/api:streams/internal-test@all-autogates-enabled	0.4s	0.3s	-0.1s	-25.0%
//src/workerd/api:streams/standard-test	0.5s	0.4s	-0.1s	-20.0%
//src/workerd/api:streams/standard-test@all-autogates-enabled	0.6s	0.5s	-0.1s	-16.7%
//src/workerd/api:tests/fetch-test	0.4s	0.3s	-0.1s	-25.0%
//src/workerd/api:tests/response-json	0.4s	0.3s	-0.1s	-25.0%
//src/workerd/api/node:tests/bound-als-test	0.5s	0.4s	-0.1s	-20.0%
//src/workerd/api/node:tests/module-create-require-test	0.4s	0.3s	-0.1s	-25.0%
//src/workerd/jsg:iterator-test	0.4s	0.3s	-0.1s	-25.0%
//src/workerd/jsg:ser-test@all-autogates-enabled	0.4s	0.3s	-0.1s	-25.0%
//src/workerd/server/tests/inspector:inspector-test	1.9s	1.3s	-0.6s	-31.6%

[danlapid]

This should not be merged until well after we rolled fastapi to all traffic slowly as an autogate.
If we decide to do that.