honor content_format clientcap

This removes all markdown when the client does not support the markdown MarkupKind

Otherwise the output on the editor will have some markdown boilerplate, making it less readable

crates/rust-analyzer/src/handlers.rs

@@ -618,7 +618,11 @@ pub(crate) fn handle_hover(
 ) -> Result<Option<lsp_ext::Hover>> {
     let _p = profile::span("handle_hover");
     let position = from_proto::file_position(&snap, params.text_document_position_params)?;
-    let info = match snap.analysis.hover(position, snap.config.hover.links_in_hover)? {
+    let info = match snap.analysis.hover(
+        position,
+        snap.config.hover.links_in_hover,
+        snap.config.hover.markdown,
+    )? {
         None => return Ok(None),
         Some(info) => info,
     };