Hi, first of all: Thanks for this great and simple block!

Currently I'm adding a custom block variation to add a "Copy Link" block (similar to #6). But for replacing the url, label and icon I need to use some nasty regex. Well actually, for url and label I can use the new WP_HTML_Tag_Processor, but for replacing the SVG icon in the render_block_outermost/social-sharing-link I need regex.

Would you accept a PR that adds a simple filter hook at the end of get_link_services, which could be used to add custom services or replace an icon. Of course, extenders would still need to register their variations in the editor.

Since I've already got it running, I could also provide a PR for #6, allthough that needs frontend JS and I'm not sure if you want to include that in your plugin.