cache/filecache: Unable to resolve the :resourceDir token

[jmooring]

While working on #14094, I encountered an issue where the compiled value of caches.misc.dir does not correctly resolve the :resourceDir token.

The :cacheDir token works as expected when used in the uncompiled value, but :resourceDir currently resolves to an empty string.

Many years ago, the :resourcedir token was resolved to a specific path. However, in 2018, this behavior was changed to resolve the token to an empty string.

Here's the diff:

f9b4eb4#diff-1001eddce35a486c3212a0e83856f4d13ed76f50834bc6aee008416e2d61ca9aL184

[jmooring]

See #14167 (comment).