Relocate functions related to conformance

[ethanzhouyc]

Currently, some functions related to features and conformance do not fit well within any existing files. For better code structure, these functions should be moved to a new module (directory or file).

For example, in PR #1513, the current placement of getEndpointTypeElements cannot fit into any query DB files. All functions related to conformance expression parsing should be moved out of query-feature.js as it is not related to DB queries.