BUG/MEDIUM: quic: Buffer overflow when looking through QUIC CLI keyword list

This has been detected by libasan as follows:

=================================================================
==3170559==ERROR: AddressSanitizer: global-buffer-overflow on address 0x55cf77faad08 at pc 0x55cf77a87370 bp 0x7ffc01bdba70 sp 0x7ffc01bdba68
READ of size 8 at 0x55cf77faad08 thread T0
    #0 0x55cf77a8736f in cli_find_kw src/cli.c:335
    #1 0x55cf77a8a9bb in cli_parse_request src/cli.c:792
    #2 0x55cf77a8c385 in cli_io_handler src/cli.c:1024
    #3 0x55cf77d19ca1 in task_run_applet src/applet.c:245
    #4 0x55cf77c0b6ba in run_tasks_from_lists src/task.c:634
    #5 0x55cf77c0cf16 in process_runnable_tasks src/task.c:861
    #6 0x55cf77b48425 in run_poll_loop src/haproxy.c:2934
    #7 0x55cf77b491cf in run_thread_poll_loop src/haproxy.c:3127
    #8 0x55cf77b4bef2 in main src/haproxy.c:3783
    #9 0x7fb8b0693d09 in __libc_start_main ../csu/libc-start.c:308
    #10 0x55cf7764f4c9 in _start (/home/flecaille/src/haproxy-untouched/haproxy+0x1914c9)

0x55cf77faad08 is located 0 bytes to the right of global variable 'cli_kws' defined in 'src/quic_conn.c:7834:27' (0x55cf77faaca0) of size 104
SUMMARY: AddressSanitizer: global-buffer-overflow src/cli.c:335 in cli_find_kw
Shadow bytes around the buggy address:

According to cli_find_kw() code and cli_kw_list struct definition, the second
member of this structure ->kw[] must be a null-terminated array.
Add a last element with default initializers to <cli_kws> global variable which
is impacted by this bug.

This bug arrived with this commit:
   15c74702d MINOR: quic: implement a basic "show quic" CLI handler

Must be backported to 2.7 where this previous commit has been already
backported.

src/quic_conn.c

@@ -7833,6 +7833,7 @@ static void cli_release_show_quic(struct appctx *appctx)
 
 static struct cli_kw_list cli_kws = {{ }, {
 	{ { "show", "quic", NULL }, "show quic : display quic connections status", cli_parse_show_quic, cli_io_handler_dump_quic, cli_release_show_quic },
+	{{},}
 }};
 
 INITCALL1(STG_REGISTER, cli_register_kw, &cli_kws);