PostgreSQL: initial support (MVP)

[jufajardini]

PostgreSQL: add SSL handshake support
-- applayerpgsql/parser: add parsers for request and response messages
-- applayerpgsql/pgsql: add unittests for parse_response
-- this parser does not yet handle what happens after the handshake

Make sure these boxes are signed before submitting your Pull Request -- thank you.

• I have read the contributing guide lines at https://redmine.openinfosecfoundation.org/projects/suricata/wiki/Contributing
• I have signed the Open Information Security Foundation contribution agreement at https://suricata-ids.org/about/contribution-agreement/
• I have updated the user guide (in doc/userguide/) to reflect the changes made (if applicable)

Link to redmine ticket:
https://redmine.openinfosecfoundation.org/issues/4241

Previous PR (draf): #5830

Describe changes:

• applayerpgsql/parser: add parsers for request and response messages
• applayerpgsql/pgsql: add unittests for parse_response
• this parser does not yet handle what happens after the handshake
• fix inconsistency with ALPROTO_PGSQL in some places and ALPROTO_POSTGRESQL in others

#suricata-verify-pr: OISF/suricata-verify#433
#suricata-verify-repo:
#suricata-verify-branch:
#suricata-update-pr:
#suricata-update-repo:
#suricata-update-branch:
#libhtp-pr:
#libhtp-repo:
#libhtp-branch:

[codecov]

Codecov Report

Merging #5832 (eacb800) into master (62e665c) will decrease coverage by 0.00%.
The diff coverage is 59.75%.

@@            Coverage Diff             @@
##           master    #5832      +/-   ##
==========================================
- Coverage   72.38%   72.38%   -0.01%     
==========================================
  Files         604      606       +2     
  Lines      179369   179452      +83     
==========================================
+ Hits       129837   129891      +54     
- Misses      49532    49561      +29     

Flag	Coverage Δ
suricata-verify	49.16% <58.02%> (+0.01%)	⬆️
unittests	63.05% <14.63%> (-0.03%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

[jufajardini]

Closed with: #5841