REGTESTS: ssl: add a PEM with mix of LF and CRLF line endings

REGTESTS: ssl: add a PEM with mix of LF and CRLF line endings

User tried to update a PEM, generated automatically. Part of this PEM has LF
line endings, and another part (CA certificate), added by some API, has CRLF
line endings. This has revealed a bug in cli_snd_buf(), see more
details in issue GitHUB #2818. So, let's add an example of such PEM in our
SSL regtest.

(cherry picked from commit ea4a148a7d9ead2132757bffd4699146e80da2df)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit 296cbefc98f76862111170b8a7b3aeb8d88d107d)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>