feat: add output icon tests

This PR integrates test cases aimed at validating the correct output and rendering of the icons on each package.

Details:

Added a test to validate that all generated icons are valid and contain valid SVG elements.
Tests were added that validate the output of the following icon packages:
- Validate that Tabler icons do not contain a stroke that malformed the generated icons.
- path elements generated in Remix icons must have fill="currentColor" to render correctly.
- Elements that use two tones in Ant Design Icons should be the only ones that have fill-opacity="0.6"

Problems detected by these same tests were also corrected:

A VSCode icon had no content.
A Table icon defaults to a stroke="#010202"
Some Ant Design icons were getting a fill-opacity="0.6" due to the way they were being validated if they were two tone icons.
The SVG wrapper was failing to get the stroke from the attributes even though it was not present.

The next step with this would be to integrate the tests into Github actions and validate each PR with these tests.

x64Bits / solid-icons