[VS] Rename REST API

[NicoMaio]

Rename the vulnerability scan API following the ntopng standards.

[NicoMaio]

• /lua/rest/v2/add/host/to_scan.lua (Add Host to vulnerability scan hosts list) -> /lua/rest/v2/add/vs/entry.lua
• /lua/rest/v2/exec/host/schedule_vulnerability_scan.lua -> /lua/rest/v2/exec/vs/schedule.lua
• /lua/rest/v2/get/host/vulnerability_scan_type_list.lua -> /lua/rest/v2/get/vs/types.lua
• /lua/rest/v2/get/host/to_scan_list.lua -> /lua/rest/v2/get/vs/entries.lua
• /lua/pro/rest/v2/get/vs/report_list.lua -> /lua/pro/rest/v2/get/vs/reports.lua
• /lua/rest/v2/edit/host/update_va_scan_period.lua -> /lua/rest/v2/edit/vs/periodicities.lua

[MatteoBiscosi]

Not needed