feat(nsis): Add flag to force start on silent install

If --force-run flag is specified on installer then will start the app on silent install
Exposed forceRun flag on NSIS updater quit and install, default value is false

electron-userland#1545

packages/electron-builder/templates/nsis/common.nsh

@@ -54,6 +54,15 @@ Name "${PRODUCT_NAME}"
 !macroend
 !define Updated `"" Updated ""`
 
+!macro _ForceRun _a _b _t _f
+  ClearErrors
+  ${GetParameters} $R9
+  ${GetOptions} $R9 "--force-run" $R8
+  IfErrors `${_f}` `${_t}`
+!macroend
+!define ForceRun `"" ForceRun ""`
+
+
 !macro extractEmbeddedAppPackage
   !ifdef COMPRESS
     SetCompress off

packages/electron-builder/templates/nsis/installSection.nsh

@@ -210,6 +210,7 @@ ${endif}
 !ifdef ONE_CLICK
   !ifdef RUN_AFTER_FINISH
     ${IfNot} ${Silent}
+    ${OrIf} ${ForceRun}
       # otherwise app window will be in backround
       HideWindow
       !insertmacro StartApp

packages/electron-updater/src/NsisUpdater.ts

@@ -134,17 +134,17 @@ export class NsisUpdater extends AppUpdater {
 
     this.app.on("quit", () => {
       this._logger.info("Auto install update on quit")
-      this.install(true)
+      this.install(true, false)
     })
   }
 
-  quitAndInstall(isSilent: boolean = false): void {
-    if (this.install(isSilent)) {
+  quitAndInstall(isSilent: boolean = false, forceRunAfter: boolean = false): void {
+    if (this.install(isSilent, forceRunAfter)) {
       this.app.quit()
     }
   }
 
-  private install(isSilent: boolean): boolean {
+  private install(isSilent: boolean, forceRunAfter: boolean): boolean {
     if (this.quitAndInstallCalled) {
       return false
     }
@@ -163,6 +163,11 @@ export class NsisUpdater extends AppUpdater {
     if (isSilent) {
       args.push("/S")
     }
+
+    if (forceRunAfter) {
+      args.push("--force-run")
+    }
+
     const spawnOptions = {
       detached: true,
       stdio: "ignore",