Eglot: spectacular optimization in files with many diagnostics

In a large (or simply long) file with many diagnostics, calling
eglot-range-region repeteadly constantly throws Emacs for a spin
around the buffer, since each diagnostics comes annotated with a
(line/col): LSP range spec that is reasonably expensive to
translate into Elisp point positions.

A much faster approach for such large lists is to first sort all the
objects containing ranges by their start lines and then do a
single pass of the buffer, moving lines by delta.

By much faster, I do mean spectacularly (100x) faster. A long python
with 7000 "ruff" diagnostics, before the change, typical editor
operations (add/delete words) are impossible.

       14053  84%    - jsonrpc-connection-receive
       14052  84%     - #<byte-code-function B94>
       14052  84%      - apply
       14052  84%       - eglot-handle-notification
       14052  84%        - applyn
       14052  84%         - #<byte-code-function 6DB>
       14052  84%          - eglot--flymake-handle-push
       12295  74%           - eglot--flymake-make-diag
       12218  73%            + eglot-range-region
          50   0%            + eglot--check-object
          12   0%              plist-member
           3   0%              flymake-make-diagnostic

After the change:

          99   1%    - jsonrpc-connection-receive
          99   1%     - #<byte-code-function 0EE>
          99   1%      - apply
          99   1%       - eglot-handle-notification
          99   1%        - apply
          99   1%         - #<byte-code-function E84>
          99   1%          - eglot--flymake-handle-push
          99   1%           - eglot--call-with-ranged
          99   1%            - #<byte-code-function 2C6>
          99   1%             - eglot-move-to-utf-16-linepos
          99   1%                line-end-position

* lisp/progmodes/eglot.el (eglot-move-to-linepos-function):
Forward declare.
(eglot--call-with-ranged, eglot--collecting-ranged): New helpers.
(eglot--flymake-report-1)
(eglot--imenu-SymbolInformation): Use eglot--collecting-ranged.
(eglot--imenu-DocumentSymbol): Could use eglot--collecting-ranged.

* etc/EGLOT-NEWS: Mention it

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