modules: add support for conflict in lua modulefile (#36701)

Add support for conflict directives in Lua modulefile like done for Tcl
modulefile.

Note that conflicts are correctly honored on Lmod and Environment
Modules <4.2 only if mutually expressed on both modulefiles that
conflict with each other.

Migrate conflict code from Tcl-specific classes to the common part. Add
tests for Lmod and split the conflict test case in two.

Co-authored-by: Massimiliano Culpo <massimiliano.culpo@gmail.com>

share/spack/templates/modules/modulefile.lua

@@ -69,6 +69,12 @@ setenv("LMOD_{{ name|upper() }}_VERSION", "{{ version_part }}")
 depends_on("{{ module }}")
 {% endfor %}
 {% endblock %}
+{#  #}
+{% block conflict %}
+{% for name in conflicts %}
+conflict("{{ name }}")
+{% endfor %}
+{% endblock %}
 
 {% block environment %}
 {% for command_name, cmd in environment_modifications %}