Provide new workflow to package .vsix

[fantavlik]

I was noticing that the .vsix generated for release using vsce package is very dependent on the individual user's environment so I wanted to provide a way to make this more reproducible in CI.

The workflow is triggered when a new tag is pushed, a test tag run can be seen here after I pushed the 0.3.1-beta1 tag: https://github.com/splunk/vscode-extension-splunk/actions/runs/5571074169

Under the job summary a zip file containing the generated .vsix can be seen at the bottom of the page under Artifacts:

Two other fixes that were made

• Added an overrides section to account for peer dependencies using older incompatible versions of react, react-dom and styled-components, these changes match the 0.3.0 release so there shouldn't be any actual dependency changes here 🤞
• Added (back) some axios header code to handle various versions of axios in a backwards compatible way - npm was resolving this dependency in various ways and this ensures that all versions of axios will work out-of-the-box