[BUG] tls_mgm mysql schema limit for ca_list field

[vasilevalex]

OpenSIPS version you are running

version: opensips 2.4.5 (x86_64/linux)
flags: STATS: On, DISABLE_NAGLE, USE_MCAST, SHM_MMAP, PKG_MALLOC, F_MALLOC, FAST_LOCK-ADAPTIVE_WAIT
ADAPTIVE_WAIT_LOOPS=1024, MAX_RECV_BUFFER_SIZE 262144, MAX_LISTEN 16, MAX_URI_SIZE 1024, BUF_SIZE 65535
poll method support: poll, epoll, sigio_rt, select.
git revision: unknown
main.c compiled on 08:33:39 May 23 2019 with gcc 4.8.5

Describe the bug
mysql schema for tls_mgm module has column ca_list for list of CA certificates, type is BLOB. But BLOB has max size 65535 bytes. It is enough for certificate or for private key, but of course not enough for list of trusted certificates. In CentOS this list is about 211K, Debian 235K. So ca_list should be of MEDIUMBLOB type.

To Reproduce

1. Store OS trusted root certificates to MySQL ca_list of any TLS domain.
2. Read ca_list from MySQL. It will be only 64K size.

Expected behavior
130-150 certificates can take more than 64K size. It should be possible to store them in DB.

Relevant System Logs
No errors in logs.

OS/environment information

• Operating System: CentOS 7
• OpenSIPS installation: git