Remove some features in favor of the official pwa plugin

[pradeep910]

With the latest official PWA plugin releasing we will get some features already in it.

Following work we need to do in PWA Extension to make it work well with official PWA plugin:

• Remove "Add home to screen" work
• Remove Assets caching feature
• Remove Navigation caching feature
• Add Code snippet to enable SVG files caching in uploaded images cache. (mostly we use SVG logos which don't get offline cached due to svg restriction)

add_filter( 'ext2type', static function ( $ext2type ) {
	$ext2type['image'][] = 'svg';
	return $ext2type;
} );

In our internal QA we found these issues:

• Enabled both PWA main and rt PWA extension plugin and performed quick sanity and following are the observations.
• If both plugins are active then Add to home screen is not appearing. If only PWA main plugin is active Add to home screen is appearing
• Offline reading is working as expected
• If both plugins are active then the Navigation cache and Uploaded images are not getting created.