Nested components are not validated

Problem/Motivation

While writing custom validators for a huge multi-page form with several layers of nesting where several of the lower components use the same form key(but on different 'branches'), I noticed some of my validators weren't getting executed. Some other validators got executed even though no components on the current page were involved in the rules using them.

This came down to the rules being filtered out because no form keys matched the components on the page. The main issue was that the function getting the form key from the component only returns the key part for the lowest level. Sometimes that matched no components and sometimes it matched other components, depending on which other components using the same last part of the key were present.

Proposed resolution

Filtering out rules by form key got more complicated when comparing the full keys gotten by iterating through all component parents, so I started looking for another way, preferably using the component id. Turns out that works well since the flat list of form values is already indexed by component id, and any components not included on the page are already excluded from it.

Remaining tasks

Review, test.

User interface changes

None

API changes

Two functions removed (not needed anymore): webform_validation_get_field_keys() and webform_validation_rule_get_formkeys().
These functions would not properly handle nested keys and only considered the lowest level.

Data model changes

None