Avoid recursive process filters in lisp/jsonrpc.el (bug#60088)

Avoid recursive process filters in lisp/jsonrpc.el (bug#60088)

jsonrpc.el may lose JSON-RPC messages because of recursive process
filters.  The problem happens in jsonrpc.el's jsonrpc--process-filter.

The code of the process filter didn't expect to be called recursively
and fails in that case.

But that can happen if the three conditions are verified.

1. the client code invoked by its jsonrpc--connection-receive inside
   the process filter callee immediately sends follow-up input to
   process within the same Lisp stack.  This is a common scenario,
   especially during LSP initialiation sequence used by Eglot, a
   jsonrpc.el client.

2. that follow-up message is large enough for process-send-string to
   send the input in bunches (output from processes can arrive in
   between bunches).

3. the process happens to have already some more output ready

The fix in this commit detects recursive invocations and immediately
re-schedules them as non-recursive calls to the
jsonrpc--process-filter (but started from timers).

* lisp/jsonrpc.el (jsonrpc--process-filter): Rework.
(Version): Bump to 1.0.16.