Fix a bug of find widget

[SiriusXT]

When finding, if you delete a find result in the note and then click to find the next one, an error will occur:

CKEditorError: mapping-model-position-view-parent-not-found {"modelPosition":{"root":"$graveyard","path":[0],"stickiness":"toNext"}}
Read more: https://ckeditor.com/docs/ckeditor5/latest/support/error-codes.html#error-mapping-model-position-view-parent-not-found
    at Nc.on.priority (<anonymous>:6:643867)
    at Nc.fire (<anonymous>:6:470940)
    at Nc.toViewPosition (<anonymous>:6:646343)
    at Nc.toViewRange (<anonymous>:6:646082)
    at n_.<anonymous> (<anonymous>:6:1032187)
    at m (<anonymous>:6:602325)
    at f (<anonymous>:6:602550)
    at p (<anonymous>:6:602439)

This pr makes it necessary to update the find results after modifying a note and then clicking on Find Previous and Next.

[eliandoran]

LGTM.