Allow svgs with titles to keep them after svgo optimization

[paulrudy]

Thanks for this plugin! I have a suggestion:

It looks like svgo's removeTitle plugin is enabled by default.

While I learned from #36 that there is a prop for adding a title to an svg, I think it would be helpful to permit svg's that already have a title embedded to keep their titles, without needing to re-add them.

Perhaps either svgo's removeTitle plugin could be optionally disabled, or perhaps there could be a prop for astro-icon to preserve any already-existing title?

[stramel]

I believe this will be addressed in the v1 branch.