storaged: Type contains_rootfs()

This function calls itself recursively, so the type checker cannot infer
its signature. Add one explicitly.

Fixes

> pkg/storaged/crypto/keyslots.jsx(405,44): error TS7024: Function implicitly has return type 'any' because it does not have a return type annotation and is referenced directly or indirectly in one of its return expressions.

which is the last remaining instance of that error. So stop ignoring it.

pkg/storaged/crypto/keyslots.jsx

@@ -387,6 +387,7 @@ function ensure_non_root_nbde_support(steps, progress, client, block) {
             .then(() => ensure_crypto_option(steps, progress, client, block, "_netdev"));
 }
 
+/** @type (client: any, path: string) => boolean */
 function contains_rootfs(client, path) {
     const block = client.blocks[path];
     const crypto = client.blocks_crypto[path];

test/common/typecheck

@@ -76,7 +76,6 @@ javascript_ignored_codes = [
     "TS7019",   # Rest parameter '*' implicitly has an 'any[]' type
     "TS7022",   # '*' implicitly has type 'any'...
     "TS7023",   # '*' implicitly has return type 'any' because ...
-    "TS7024",   # Function implicitly has return type 'any' because ...
     "TS7031",   # Binding element '*' implicitly has an 'any' type.
     "TS7034",   # Variable '*' implicitly has type 'any' in some locations where its type cannot be determined.
     "TS7053",   # Element implicitly has an 'any' type because expression of type 'any' can't be used to