Feat: Add option to pass a port for development server

[ayushnirwal]

Description

Adds a new argument to the CLI interface '--dashboard-port' or '-po' which can be used to launch the CLI server on a chosen port.

Relevant Technical Choices

• Naming the new argument CLI interface '--dashboard-port' or '-po'.
• Add a check that the user has chosen options for the dashboard to be launched before checking for any port conflicts.

Testing Instructions

• Use the cli command npm run cli -- -u https://edition.cnn.com -po 9009
• CLI dashboard should be launched on the chosen port.
• A service running on chosen port should not effect the CLI's functioning if its run in headless mode. npm run cli -- -u https://edition.cnn.com -d ./out

Checklist

• I have thoroughly tested this code to the best of my abilities.
• I have reviewed the code myself before requesting a review.
• This code is covered by unit tests to verify that it works as intended.
• The QA of this PR is done by a member of the QA team (to be checked by QA).

Fixes #573