[WC-2984] Events: Parameter type support

[yordan-st]

Pull request type

New feature (non-breaking change which adds functionality)

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Description

When configuring the Events widget to run specific action on load or on attribute change, previously user only could set a static value when setting the delay value or repeat interval.

I enhanced this by adding a the possibility to set these value with expressions. This way users have more flexibility when configuring their events.

What should be covered while testing?

• Toggling 'Value' or 'Expression' should display the correct property
• When a user configures expressions to calculate the delay or paramater value, this should be correctly set to the expected value

[r0b1n]

There is dynamicValue helper for this, in the same place where actionValue is coming from.

[r0b1n]

As originally property was called componentLoadRepeatInterval (and should stay this way, old names can't be changed), isn't componentLoadRepeatIntervalExpression is a better name?
Same for componentLoadRepeatParameterType -> componentLoadRepeatIntervalParameterType.

Previously we had componentLoadRepeatInterval - componentLoad is prefix, forget about that for a moment. So we have
RepeatInterval as number, and we need to extend the properties, so we need following properties:

(Repeat interval) Parameter Type (switch between types)
(Repeat interval) Static (for static number )
(Repeat interval) Expression (for expression)

So logical names would be
[prefix]RepeatIntervalParameterType
[prefix]RepeatIntervalStatic
[prefix]RepeatIntervalExpression

So far so good, but because static property already existed there under name [prefix]RepeatInterval, we have to keep it, so even though it is a bit inconvenient naming we have to do the following:

[prefix]RepeatIntervalParameterType
[prefix]RepeatInterval (old name, so that property value is not getting lost)
[prefix]RepeatIntervalExpression

Hope this makes sense.

Check other names and standardize the convention behind those names.