Add multi-process support for download progress notifications during client reset download

[sync-by-unito]

Create a design and add multi-process support for download progress notifications while the fresh realm is being downloaded during a client reset.

Need to determine if this is even possible, but it may involve writing the fresh realm progress to the client history download values, unless there is somewhere else where this info can be stored and accessed by the other processes.

[sync-by-unito]

➤ PM Bot commented:

Jira ticket: RCORE-2237

[sync-by-unito]

➤ michael-wb commented:

Spoke with Thomas regarding this today:
The proposed solution is to repurpose the existing downloadable and downloaded values in the client history to store the client reset fresh realm download progress and add a new function to set these values during the download:

static void set_temporary_download_progress(Transaction& tr, DownloadableProgress downloadable,
                                            uint64_t downloaded);