Add webpack build config

[nickofthyme]

Is your feature request related to a problem? Please describe.
I want a more configurable build. Allow for watch mode for built assets.

Describe the solution you'd like
Combine all build scripts into webpack.config.js file. This would facilitate yarn linking of @elastic-charts into other codebases, for seamless debugging.

Describe alternatives you've considered
Use watchman to watch file changes and build everything over again.

Checklist

• this request is checked against already exist requests
• every related Kibana issue is listed under Kibana Cross Issues list
• kibana cross issue tag is associated to the issue if any kibana cross issue is present

[markov00]

@nickofthyme can we close this within #1164 ?

[nickofthyme]

I think the main issue here is fixed but I would still like to have our chart builds run by webpack or vite instead of tsc.