Add missing DLC content and include thumbnail images

[WerewolfCustoms]

As Mikey showed on #ms2dev - inlcude some common tumbnails

Optional:

• add thumbnails for trucks

[pete-agreatguy]

... ModsStudio2Library\Models\ScsMod\Data... lists

• [x] SCS DLCs listed in manifest section - ats
• [x] SCS DLCs listed in manifest section - ets2
• [x] Add missing ATS DLC to DLC list in manifest
• [x] Add missing ETS2 DLC to DLC list in manifest

... moved other requirements to #442

Sources:

ATS = https://store.steampowered.com/dlc/270880/American_Truck_Simulator/

ETS2 = https://store.steampowered.com/dlc/227300/Euro_Truck_Simulator_2/

[pete-agreatguy]

@WerewolfCustoms Where would you prefer I store the thumbnail images for DLC and companies?

Within (A) "... Mods Studio 2\UI\Resources\Thumbnails"

Or (B) in "... Mods Studio 2\Data\ModData\SCS\Thumbnails" ???

[WerewolfCustoms]

Option B 👍

[pete-agreatguy]

Use ATS depot sign images from "extracted_149\model\sign\company_logos"