Add Fortigate Fortinet index to multiple detection rules

[SHolzhauer]

Pull Request

Issue link(s):
Resolves #4268

Summary - What I changed

Did a bit of a dive into the mentioned rules and how they map to the fortinet fortigate integration

rule name	observation	should work	update required
RPC (Remote Procedure Call) to the Internet	The integration has the relevant fields	y	the index should be updated to include the integration
RPC (Remote Procedure Call) from the Internet	The integration has the relevant fields	y	the index should be updated to include the integration
VNC (Virtual Network Computing) to the Internet	The integration has the relevant fields	y	the index should be updated to include the integration
VNC (Virtual Network Computing) from the Internet	The integration has the relevant fields	y	the index should be updated to include the integration
Accepted Default Telnet Port Connection	Unsure if the event.action will match with the fortinet logs
Roshal Archive (RAR) or PowerShell File Downloaded from the Internet	The integration has the relevant fields	y	the index should be updated to include the integration
Possible FIN7 DGA Command and Control Behavior	no type field exported by fortinet
IPSEC NAT Traversal Port Activity	The integration has the relevant fields	y	the index should be updated to include the integration
SMTP on Port 26/TCP	The integration has the relevant fields	y	the index should be updated to include the integration
Potential Network Sweep Detected	The integration has the relevant fields	y	the index should be updated to include the integration
Potential Network Scan Detected	Unsure if the event.action will match with the fortinet logs
Potential SYN-Based Network Scan Detected	The integration has the relevant fields	y	the index should be updated to include the integration
RDP (Remote Desktop Protocol) from the Internet	The integration has the relevant fields	y	the index should be updated to include the integration
SMB (Windows File Sharing) Activity to the Internet

How To Test

Checklist

• Added a label for the type of pr: bug, enhancement, schema, maintenance, Rule: New, Rule: Deprecation, Rule: Tuning, Hunt: New, or Hunt: Tuning so guidelines can be generated
  - [ ] Added the meta:rapid-merge label if planning to merge within 24 hours
• Secret and sensitive material has been managed correctly
  - [ ] Automated testing was updated or added to match the most common scenarios
  - [ ] Documentation and comments were added for features that require explanation

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