Action to alter webform element

Problem/Motivation

ECA webform already exposes the alter element event in ECA, but as far as I know, it is not yet possible to set the element properties through any ECA action since the respective tokens are read-only.

My use case is to dynamically update the cardinality of a webform element based on a field value in the webform submission's source entity.
Without using ECA, doing so involves:

1. Implementing hook_webform_element_alter()
2. Checking if the element is a multi-value input field by checking the value of $element['#multiple']
3. Loading source entity through $form_state->getFormObject()->getSourceEntity()
4. Load field value of source entity
5. Setting the value of $element['#min_value'] to the field value
6. Set $element['#add'], $element['#remove'], and $element['#add_more'] to FALSE

Currently, step 1 is already implemented in ECA webform, step 4 is possible through ECA content. Step 2 may be possible as well by just using ECA base and checking token values. Steps 3, 5, and 6 are not possible to perform.

Steps to reproduce

Proposed resolution

• Add a new action to load source entity OR add source entity to event tokens
• Add an action to use YAML key-value pairs to set $element properties.

Remaining tasks

User interface changes

API changes

Data model changes