fix(rage-device-rdr3): ignore memory backed pack files

[DaniGP17]

Goal of this PR

Some packfiles generated by Red Dead Online (e.g. catalog_mp.rpf / catalog_awards_mp.rpf) are not stored on disk but are dynamically mounted into memory by RAGE as memory-backed virtual packfiles. These files do not represent user-modified game data, but runtime DLC/ progression catalogs that only exist transiently while the Online environment is active.
Since they are not real RPFs on disk, attempting to validate them under pure mode would incorrectly flag them as modified because memory-backed packfiles are unencrypted and their hashes are derived from encrypted on-disk data.

How is this PR achieving the goal

Nop the function that start mounting memory-backed virtual packfiles.

This PR applies to the following area(s)

RedM

Successfully tested on

Game builds: 1491
Platforms: Windows

Checklist

• Code compiles and has been tested successfully.
• Code explains itself well and/or is documented.
• My commit message explains what the changes do and what they are for.
• No extra compilation warnings are added by these changes.

Fixes issues

fixes #3499 (comment)