detect/ftp.command: Add sticky buffer

[jlucovsky]

Continuation of #12428

Issue: 7502

Add a sticky buffer for "ftp.command" for matching on FTP command names.

Link to ticket: https://redmine.openinfosecfoundation.org/issues/7502

Describe changes:

• Add a sticky buffer for ftp.command
• Briefly document ftp.command sticky buffer.

Updates

• Rebase
• Documentation for supported ftp rule keywords.

Provide values to any of the below to override the defaults.

• To use an LibHTP, Suricata-Verify or Suricata-Update pull request,
  link to the pull request in the respective _BRANCH variable.
• Leave unused overrides blank or remove.

SV_REPO=
SV_BRANCH=OISF/suricata-verify#2245
SU_REPO=
SU_BRANCH=
LIBHTP_REPO=
LIBHTP_BRANCH=

[codecov]

Codecov Report

Attention: Patch coverage is 50.00000% with 18 lines in your changes missing coverage. Please review.

Project coverage is 80.62%. Comparing base (95e8427) to head (2e5ceee).

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #12439      +/-   ##
==========================================
- Coverage   80.63%   80.62%   -0.01%     
==========================================
  Files         920      921       +1     
  Lines      258704   258740      +36     
==========================================
+ Hits       208595   208621      +26     
- Misses      50109    50119      +10     

Flag	Coverage Δ
fuzzcorpus	56.81% <50.00%> (-0.01%)	⬇️
livemode	19.40% <50.00%> (+<0.01%)	⬆️
pcap	44.30% <50.00%> (-0.04%)	⬇️
suricata-verify	63.25% <50.00%> (-0.02%)	⬇️
unittests	58.52% <50.00%> (-0.01%)	⬇️

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

[victorjulien]

Docs need some attention

[victorjulien]

why is this removed?

[suricata-qa]

Information: QA ran without warnings.

Pipeline 24314

[jlucovsky]

Continued in #12457