Update Logging in Test Beats

[leelaprasadv]

Summary

• Update minimum nodeJS version to >=14.0.0 to avoid issues with "#" private naming convention in lower NodeJS versions (ex: 12.x.x). Changes also include version check logic for future cases.
• MIN_NODE_VERSION controlled via src/helpers/constants.js
• Update Shields in ReadMe
• Minor log improvements
• Fixed failing tests

Log Improvements
Error when incorrect config file provided

npx testbeats@latest publish -c invalid-path-config.json 
🥁 TestBeats v2.0.4
💻 Environment Details - NodeJS v18.20.1, OS: darwin, Version: 23.4.0, arch: arm64
Report publish failed: Failed to read config file: '/testbeats/invalid-path-config.json' with error: 'Cannot find module '/testbeats/invalid-path-config.json'
Require stack:
- /testbeats/src/commands/publish.command.js
- /testbeats/src/cli.js'

Unsupported NodeJS version (with exception to v12.0.0, fails with unhandled exception)

PS: NodeJS min version bumped to 16.x for below demo.

🥁 TestBeats v2.0.4
Report publish failed: ❌ Supported NodeJS version is >= v16.0.0. Current version is v14.20.0

Successful results publish

🥁 TestBeats v2.0.4
💻 Environment Details - NodeJS v18.20.1, OS: darwin, Version: 23.4.0, arch: arm64
🛠️ Validating configuration...
🧙 Processing results...
😿 No API key provided, skipping publishing results to TestBeats Portal...
✅ Results published successfully!