bug#72597: 30.0.60; Eglot: MarkedString with embedded Carriage Return

[Troy Brown <brownts@troybrown.dev>]

With the LSP language server I'm using, it's possible the language
server will return a textDocument/hover response MarkedString
containing "\r" (i.e., carriage return) for the line terminator when
the content contains multiple lines.  An example of a typical response
is as follows:

[jsonrpc] e[19:19:44.606] <-- textDocument/hover[38]
{"jsonrpc":"2.0","id":38,"result":{"contents":[{"language":"gpr","value":"type
Library_Kinds is (\"relocatable\", \"static\",
\"static-pic\");\rLibrary_Kind : Library_Kinds :=
\"static\";"},"gtkada_shared.gpr:37:04"]}}

The font locking is performed correctly (as the highlighting looks
fine), but when the content is placed in the *eldoc* buffer, content
surrounding the carriage return is not placed on separate lines.
Instead it remains on the same line and "^M" is displayed in the
buffer.

This is what I expect:

type Library_Kinds is ("relocatable", "static", "static-pic");
Library_Kind : Library_Kinds := "static";
gtkada_shared.gpr:37:04

This is what I'm observing (single line with embedded ^M):

type Library_Kinds is ("relocatable", "static",
"static-pic");^MLibrary_Kind : Library_Kinds := "static";
gtkada_shared.gpr:37:04