Native Inserter: Fix SVG rendering

[kean]

What?

• Fix CMM-873: SVG for icons for some blocks is invalid.
• Fix an issue with wpios/jpios failing to build due to some conflict with SVGKit

How?

Switch to SVGView, which is a more modern framework, and as lenient as a browser when it comes to parsing SVG. It supports shorten coordinates like 5.5h3a.5.5 that are common in Gutenberg.

One of the design choices was to enforce a particular fill color (in order to support dark mode). It works great for nearly all icons, but I found only one exception so far – "Animoto Embed". This icon uses multiple colors, and doesn't look ideal (see screenshots below). We can simply hardcode a different icon for it if we want. Note: you need to merge #204 to test the embed variants.

Testing Instructions

• Verify that no blocks display placeholder icons
• Verify that icons work in dark mode

Screenshots or screencast

Known Issues (Identified in the scope of this PR)

• CMM-905: Remove "Pattern Placeholder"
• CMM-904: Add support for deprecated blocks

(these are fixed by #199)

Screenshots (core/embed variants)

Before:

After:

[dcalhoun]

Looks sound overall. I welcome @jkmassel 's feedback on the inclusion of SVGView.

[jkmassel]

Looks sound overall. I welcome @jkmassel 's feedback on the inclusion of SVGView.

I'm not a big fan of it overall, but I think it works and it moves us forward for now. We can revisit this one later when we're implementing this on the Android side.