[JenkinsQueueJobV2] Fix job hang out after unexpected response from Jenkins

[alexander-smolyakov]

PR fix #9 and applying the following changes:

Fixes

• Fixed situation when the job hang out after unexpected response from Jenkins
• Fixed About this task link, previously it redirects on Jenkins site instead of docs.microsoft.com

Code refactor

• Resolved all tslint warnings
• Logics for checking state transition was exported into separate function - checkStateTransitions
• JobState enum and checkStateTransitions function was exported into a separate module and refactored.
• Documentation for job states was rewritten on JSdocs
• Refactored DoWork method from the Job class. The if-else was replaced on switch.
• Equals Operator was replaced on Strict Equals Operator for checking HTTP-request response. (Since this task using node package request for working with http-requests, all responses are instances of http.IncomingMessage class where statusCode type documented as number. So it's safe to use Strict Equals Operator.)

Unit tests

• Added test with the longest test scenario of the state transitions
• Added test for checking that transition rules are defined for all job states

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Testing

• Changes were tested with self-hosted windows agent and local Jenkins instance.
• All unit tests have passed.

[leantk]

Nice refactor 👍