Reduce eldoc noise from hover messages

Reduce eldoc noise from hover messages

Also close https://github.com/joaotavora/eglot/issues/985

Only echo hover response content, without response range.

LSP specification says the range is meant to visualize a hover.
Maybe echoing the range is useful for some, but it seems
non-standard behavior.

Example issue: haskell-language-server responds with range set to
whole file when hovering a comment -> Large, useless eldoc

* eglot.el (eglot--hover-info): Remove text selected by range from
output

Copyright-paperwork-exempt: Yes
GitHub-reference: fix https://github.com/joaotavora/eglot/issues/514