fix: don't throw MaxListenersExceeded error when more than 11 processes are started from sidekick

[Fatme]

In case when the user runs 11 apps from sidekick (or only 2 apps changing them 6 times),

MaxListenersExceededWarning: Possible EventEmitter memory leak detected. 11 exit listeners added. Use emitter.setMaxListeners() to increase limit

error is thrown. The problem occurs because we attach every time on process.exit and liveSyncStopped events. So this PR fixes this behavior as ensures only one listener is added for each event.

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• Tests for the changes are included.

What is the current behavior?

MaxListenersExceededWarning: Possible EventEmitter memory leak detected. 11 exit listeners added. Use emitter.setMaxListeners() to increase limit

error is thrown when the user runs 11 apps from sidekick (or only 2 apps changing them 6 times)

What is the new behavior?

No error is thrown when the user runs 11 apps from sidekick (or only 2 apps changing them 6 times)

[sis0k0]

The changes are ok. Just return the spaces instead of tabs.

[rosen-vladimirov]

With the current implementation you'll still receive the same warning in case you open 11 different projects in Sidekick (in a single instance) and run them. I think more appropriate solution is:

1. Attach only once on process.exit and liveSyncStopped event, i.e. keep the boolean flag here.
2. Whenever livesyncStopped is raised, check if you still have processes and if not - remove the process.exit and liveSyncStopped event handlers. You can do it here and reset the variable or do it in the after-watch hook.

Basically we would not need the boolean variable in case we follow the approach below:

1. On before-watch attach liveSyncStopped and process.exit handlers
2. On after-watch remove the handlers

This way, when you close a project in Sidekick, after-watch hook will be executed and we'll remove the handlers we've attached. Starting liveSync on another project will add new handlers, but we'll never add more than one process.exit handler for example (as you cannot have multiple projects working in Sidekick)

[Fatme]

run ci