Initial work on 1.13 forge resolver, fixes.

Moved java executable to its own util class.
Fixed artifact resolution links for older versions of forge.

1.13 support is going to be difficult because forge does not
make anything developer friendly.

src/resolver/forge/adapter/forge113.resolver.ts

@@ -1,4 +1,9 @@
+import { spawn } from 'child_process'
+import { copy, mkdirs, pathExists, remove, writeFile } from 'fs-extra'
+import { basename, join } from 'path'
 import { Module } from '../../../model/spec/module'
+import { ForgeRepoStructure } from '../../../model/struct/repo/forgerepo.struct'
+import { JavaUtil } from '../../../util/javautil'
 import { ForgeResolver } from '../forge.resolver'
 
 export class Forge113Adapter extends ForgeResolver {
@@ -18,11 +23,62 @@ export class Forge113Adapter extends ForgeResolver {
     }
 
     public async getModule(): Promise<Module> {
-        return null as unknown as Module
+        await this.process()
+        return {} as unknown as Module
     }
 
     public isForVersion(version: string): boolean {
         return Forge113Adapter.isForVersion(version)
     }
 
+    private async process() {
+        const forgeRepo = this.repoStructure.getForgeRepoStruct()
+        const installerPath = forgeRepo.getLocalForge(this.artifactVersion, 'installer')
+        console.debug(`Checking for forge installer at ${installerPath}..`)
+        if (!await forgeRepo.artifactExists(installerPath)) {
+            console.debug(`Forge installer not found locally, initializing download..`)
+            await forgeRepo.downloadArtifactByComponents(
+                this.REMOTE_REPOSITORY,
+                ForgeRepoStructure.FORGE_GROUP,
+                ForgeRepoStructure.FORGE_ARTIFACT,
+                this.artifactVersion, 'installer', 'jar'
+            )
+        } else {
+            console.debug('Using locally discovered forge installer.')
+        }
+        console.debug(`Beginning processing of Forge v${this.forgeVersion} (Minecraft ${this.minecraftVersion})`)
+
+        const workDir = this.repoStructure.getWorkDirectory()
+        if (await pathExists(workDir)) {
+            await remove(workDir)
+        }
+
+        await mkdirs(workDir)
+
+        const workingInstaller = join(workDir, basename(installerPath))
+
+        await copy(installerPath, workingInstaller)
+
+        // Required for the installer to function.
+        await writeFile(join(workDir, 'launcher_profiles.json'), JSON.stringify({}))
+
+        console.debug(`Spawning forge installer`)
+
+    }
+
+    private executeInstaller(installerExec: string) {
+        return new Promise((resolve, reject) => {
+            const child = spawn(JavaUtil.getJavaExecutable(), [
+                '-jar',
+                installerExec
+            ])
+            child.stdout.on('data', (data) => console.log('[Forge Installer]', data.toString('utf8')))
+            child.stderr.on('data', (data) => console.error('[Forge Installer]', data.toString('utf8')))
+            child.on('close', (code, signal) => {
+                console.log('[Forge Installer]', 'Exited with code', code)
+                resolve()
+            })
+        })
+    }
+
 }