feat: new makeSingleInstance API (#12782)

* Refactor app.makeSingleInstance
* new API `app.isPrimaryInstance()`
* new API `app.isSingleInstance()`
* new event `app.on('second-instance')`
* deprecated old syntax `app.makeSingleInstance(cb)`
* deprecated old syntax of `app.makeSingleInstance() --> bool` in favor
of `app.isPrimaryInstance()`
* Fix spec, we don't need process.nextTick hacks any more
* Make deprecation TODO for the return value of makeSingleInstance
* Refactor makeSingleInstance to requestSingleInstanceLock and add appropriate deprecation comments
* I swear this isn't tricking the linter
* Make const
* Add deprecation warnings for release, and add to planned-breaking-changes

BREAKING CHANGE

spec/fixtures/api/singleton/main.js

@@ -4,10 +4,12 @@ app.once('ready', () => {
   console.log('started')  // ping parent
 })
 
-const shouldExit = app.makeSingleInstance(() => {
-  process.nextTick(() => app.exit(0))
+const gotTheLock = app.requestSingleInstanceLock()
+
+app.on('second-instance', () => {
+  setImmediate(() => app.exit(0))
 })
 
-if (shouldExit) {
+if (!gotTheLock) {
   app.exit(1)
 }