feat: add --experiments flag to replace --experimental (#5767)

- Deprecates the --experimental flag
- Adds a new flag --experiments which supports passing multiple comma-separated values or a wildcard value.
- Exposes a new endpoint /api/v2/experiments that returns the list of enabled experiments.
- Deprecates the field Features.Experimental in favour of this new API.
- Updates apidocgen to support type aliases (shoutout to @mtojek).
- Modifies apitypings to support generating slice types.
- Updates develop.sh to pass additional args after -- to $CODERD_SHIM.

scripts/apidocgen/markdown-template/responses.def

@@ -13,6 +13,9 @@
 		if (!ref) {
 			ref = content.schema.items["x-widdershins-oldRef"];
 		}
+		if (!ref) {
+			return content.schema.items.type;
+		}
 		const aType = ref.replace("#/components/schemas/","");
 		const href = aType.replace(".","").toLowerCase();
 		return "[" + aType + "](schemas.md#" + href + ")";