add template dependencies to loader dependencies

[astik]

In its current state, only the loader's input EJS file is defined as a dependency.
It means that everytime we update the file, webpack will trigger a new processing.

Problem is when we add included file to the template with one of those directives :

<%- include('../ejs/footer.ejs') %>
<%- include ../ejs/footer.ejs %>

We can check that EJS transitive dependencies are not exposed by looking into template.dependencies content.

As this loader is a LoaderContext instance, we have access to this.dependency which allow adding dependencies to this entry file processing :

function addDependency(file) {
	fileDependencies.push(file);
}

To declare EJS dependencies, we need to bind it from EJS to the loader :

template.dependencies.forEach(this.dependency.bind(this));

[astik]

This PR will make even more sense after fixing those 2 bugs :

• Missing transitive dependencies when including template into included template mde/ejs#426
• Missing dependencies from included files (include with parenthesis) mde/ejs#427