Support for `iedit`

[failable]

Since both iedit-occurrence and lsp-face-highlight-textual both inherit from highlight, when doing iedit-mode under a LSP highlighted symbol, the faces are indistinguishable which means that it's hard to make sure if iedit is successfully enabled (though the modeline contains indicator for that).

LSP highlighted:

Note iedit is enabled in this case

[habamax]

I don't use lsp-mode, but for eglot I have defined eglot-highlight-symbol-face. Let me add the same for lsp-mode, and I will rely on you to check it :)

[habamax]

could you please check?

[failable]

Looks good! Thanks!