There are a bunch of optional commands provided by druid that trigger
this, but we only really need it to check for custom ones that weren't
implemented, yet.
Ditch the `.mod` file and move its data into the config file.
The `run` function was the only thing that could have been dynamic, but
the vast majority of mods in VT2 never made use of that. Infact, VMF was
probably the only mod that had a different content for that.
This type is similar to an `Either` between a `Murmur64` hash and a
`String`. This is necessary to be able to retain hash information where
the hash is not in the dictionary, but at the same time allow string
names where they are available.
Up until now, when reading a bundle, all hashes would be converted to
strings, which made sense for displaying those names. But when writing
the same bundle back, those strings ended up being re-hashed, resulting
in incorrect hashes.
This is mostly helpful to check/debug whether the internal dictionary
actually contains the expected data. For manually looking through the
entire dictionary, opening the CSV file is still more convenient.
There is no benefit from making all operations on binary data read
in small, async steps directly from the file.
Since we know file sizes beforehand, it's less complex to read
the entire data blob into memory once, then operate on that
synchronously.
