Since Forge 1.13.2, each mod has its own seperate folder and (Intellij/Eclipse) project
Generally, you just open the build.gradle in Intellij, select the gradle wrapper included in the repo, enable auto-import, and it should already build.
There is also a "curseforge" build target my successor can probably safely ignore.
- each mod has a build.gradle and changelog.txt, add new versions in here
Mods with special Needs, aka coremods:
-- Multi Mine -- Dynamic Lights -- Stalker Creepers -- Finder Compass