fix: webhook template should support sprig funcs

[josedonizetti]

1. Explain what the PR does

Fix #3717

This PR adds support to Sprig's funcs for webhook templates.

2. Explain how to test it

create a test.tmpl with:

{
  "hostname": "{{ .HostName }}",
  "message": "Signature name: \"{{ .Metadata.Properties.signatureName }}\" description:\n{{ .Metadata.Description }}",
  "severity": "{{ .Metadata.Properties.Severity }}",
  "time": "{{ dateInZone "2006-01-02T15:04:05Z" (now) "UTC" }}",
  "tags": {
    "category": "{{ .Metadata.Properties.Category }}",
    "external_id": "{{ .Metadata.Properties.external_id }}",
    "signature_id": "{{ .Metadata.Properties.signatureId }}"
  }
}

sudo ./dist/tracee -e anti_debugging -o webhook:http://localhost:8080?gotemplate=test.tmpl

Tracee wouldn't boot if the parse failed before.

3. Other comments

[rafaeldtinoco]

LGTM

[rafaeldtinoco]

@josedonizetti we should clear E2E before merging IMO.