Expand Drops with methods required by Liquid templates

[suleman-uzair]

Remove Liquid filters unless absolutely necessary

We do not want to add Liquid filters because they are difficult to use -- the user does not know what data types a filter acts on and what output the filter provides.

Always prefer Drop methods over custom filters.

e.g.

{{ attr | attr_type: }}

Should just be:

{{ attr.type }}

{{ attr | min_max_arg }}

Should just be:

{{ attr.cardinality }}

And any of these need to be documented.

No Metanorma-related assumptions in Liquid

lutaml-xsd does not know about Metanorma and therefore should not have anything to do with Metanorma.

When you compile the document, you can see there are cross-references called from the Liquid filter that assume the patterns of element_*, complex_type_* and attribute_group_*.

These all need to be removed.

originally posted by @ronaldtse in comment