No longer load mods from AppData

[Pathoschild]

SMAPI loads mods from two places: %appdata%\StardewValley\Mods and <install path>\Mods. This causes a lot of confusion (e.g. many users have reported problems which were traced back to having duplicate mods). Only the latter path is typically mentioned in guides, and Farmhand will only recognise that one.

To prevent confusion and smooth the eventual transition to Farmhand, no longer recognise mods in %appdata%\StardewValley\Mods as of SMAPI 1.0.

To do:

• [x] Discuss with mod authors & SMAPI developers on Discord.
• [x] Notify Silverplum author (participated in discussion to remove it).
• [x] Notify SDVMM author (see yuukiw/StardewValleyMM#11).
• [x] Notify Stardew Valley Package Manager author (discussed on Discord).
• [x] Remove support for AppData mods.

[Pathoschild]

The latest Stardew Valley Package Manager version no longer adds mods to AppData, and will move any existing mods to the standard mod folder.

[Pathoschild]

SDVMM has also been updated for compatibility.

[Pathoschild]

Done in the upcoming 1.0 release.