[feat] smart shortcut to handle several scenarios

[huyz]

This is a follow-up (and slight improvement) of https://github.com/PaulKinlan/logseq-webpage-title/pull/25#issuecomment-1186110482

I wonder if there could be a single smart shortcut:

• If the cursor is inside (or at the beginning or end of a URL), then the webpage title is fetched only for that URL (not all the URLs in the block)
• otherwise, if the cursor isn't in an URL, the clipboard is searched and if it contains only a URL, paste the URL and fetch the title.
• if an entire block is selected (not in the middle of editing a block), then fetch the titles for all URLs in the block

[PaulKinlan]

These are pretty good ideas. Will think on this.