feat(android): add WebViewAssetLoader proxy handler for cdvfile (#513)

feat(android): add WebViewAssetLoader proxy handler for cdvfile (#513)

* feat: add WebAssetLoader proxy handler for cdvfile
* fix: update the fileTarget replace string
* chore: make androidx.webkit:webkit configurable & default to 1.4.0
* feat: toURL to return file or custom scheme based on window location
* chore: remove unused variable
* chore: add other file systems to check
* chore: remove comment
* feat: bump cordova-android requirement to >=10.0.0 for AndroidX usage
* doc: updated readme to include the Android changes