Templates notifications helpers

Conditional helpers using Mustache syntax

Example: 
```
{{#if (eq object.severity 2) }}MEDIUM {{else}}Other {{/if}}
```
Find additional supported operators in [the official Handlebars documentation](https://www.javadoc.io/static/com.github.jknack/handlebars/4.1.0/com/github/jknack/handlebars/helper/ConditionalHelpers.html).

Data formatting helpers

The following helpers are available to format your data:

Helper	Description	Usage	Output
tlpLabel	Format the tlp field of the object	{{ tlpLabel object.tlp }}	Amber
papLabel	Format the pap field of the object	{{ papLabel object.pap }}	Amber
severityLabel	Format the severity field of the object	{{ severityLabel object.severity }}	Critical
dateFormat	Format a date field of the object using Java date time patterns	{{dateFormat audit._createdAt "EEEEE dd MMMMM yyyy" "fr" }}	jeudi 01 septembre 2022

Standard string helpers can be found in the official Handlebars documentation.