feat: add hostname as prefix of har filename

[cristianoventura]

Description

This PR provides a more meaningful file name for the recording based on the starting URL.

How to Test

• start a new recording
• input the starting URL
• stop the recording
• check that the generated HAR file contains hostname of the starting URL
• check that omitting the starting URL does not include any prefix

Checklist

• I have performed a self-review of my code.
• I have added tests for my changes.
• I have run linter locally (npm run lint) and all checks pass.
• I have run tests locally (npm test) and all tests pass.
• I have commented on my code, particularly in hard-to-understand areas.

Screenshots (if appropriate):

Related PR(s)/Issue(s)

Resolves #306

[going-confetti]

🚀 🚀 🚀