Adds query helpers for event properties

[aidan-casey]

This PR adds two methods wherePropertyIs() and wherePropertyIsNot() to the stored event query builder. These allow you to perform lookups against event properties and utilize the whereJsonContains methods. As an example, we have had to use this when querying for all events for a company.

Example:

EloquentStoredEvent::query()
    ->whereEvent(CompanyOptedOutOfEmails::class)
    ->wherePropertyIs('companyId', 'ABC-123-XYZ')
    ->get();

[brendt]

Great addition. Two questions:

• Should we use whereProperty or wherePropertyIs ? The PR uses the first, but your comment mentions the latter. I prefer the latter one.
• Can you add a test for this?

[aidan-casey]

1. Good catch. My intention had been wherePropertyIs for consistency, but as you mention that's not reflected in the PR. I'll update that today.

2. Definitely. 👍🏼

[aidan-casey]

@brendt - Updated with changes. Let me know what you think.

[brendt]

This is good, I'll release it together with #327

[brendt]

Tagged: https://github.com/spatie/laravel-event-sourcing/releases/tag/7.2.0