refactor: Improve readability for Execute in AppiumCommandExecutor.cs

[Dor-bl]

Change list

1. Split the execute method into 3 small methods:
   a. HandleCommandException
   b. HandleCommandCompletion
   c. HandleNewSessionCommand

2. Since I've noticed flakiness when we send commands, I've implemented a retry mechanism based on response status in the Execute method. The method now attempts command execution up to MaxRetryAttempts times, checking the success status of the response before returning. I'm still in between about this change, not sure if it's a good approach at all, all I know is that it has improved the stability of the tests.

Types of changes

What types of changes are you proposing/introducing to .NET client?
Put an x in the boxes that apply

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• New feature (non-breaking change which adds value to the project)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Documentation

• Have you proposed a file change/ PR with appium to update documentation?

This can be done by navigating to the documentation section on http://appium.io selecting the appropriate command/endpoint and clicking the 'Edit this doc' link to update the C# example

Integration tests

• Have you provided integration tests to pass against the beta version of appium? (for Bugfix or New feature)

Details

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[laolubenson]

@Dor-bl sorry i missed this PR. Did you find the reason why the execute method is flaky?

[Dor-bl]

@laolubenson, all good.
Currently trying to fix the damage I did after the latest rebase :)

[Dor-bl]

@laolubenson, I'm in between here regarding the retry mechanism, it's not so elegant but does the trick when it comes to the flakiness of the execute method.
Maybe @mykola-mokhnach & @jlipps can add their input on why we have this issue in the first place that sometimes the server fails to succeed only after the 2nd try.