Polyfills for unsupported browsers - wecodecs

[jrtcppv]

Introduce polyfills in webpack for unsupported browsers (just for best effort):

• webcodecs

(moved constructable stylesheets to new issue see comment)

[ermbutler]

Quick notes - Constructible stylesheet polyfill is introduced in #736

Need to look more into the webcodecs polyfill. Browsers without support also lack support for OffScreenCanvas which is an error that is being hit before the Codecs work. A code-fix to support these browsers as suggested by @bctcvai might be the best way to go. See: https://github.com/cvisionai/tator/issues/686

[ermbutler]

Splitting out the constructable stylesheets into new issue #757

[bctcvai]

We completed a simple video player in #686.