Bugfix: WizardBuilder removes page when saving other component with duplicate API key

[akgagnat]

Link to Jira Ticket

N/A

Description

How to reproduce the bug:

1. Go to formio sandbox
2. Change form display to 'wizard'
3. Insert a new component (e.g. Text Field) in page, provide same API key as the page and save
4. Observe error 'API key is not unique'
5. Edit component, provide a unique API key and save
6. The page has now been removed (actually replaced by the component that was changed)

What is changed in this PR:

The lookup in WizardBuilder's saveComponent event handler is done based on id instead of key.

Dependencies

N/A

How has this PR been tested?

I added unit tests.

Checklist:

• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation (if applicable)
• My changes generate no new warnings
• My changes include tests that prove my fix is effective (or that my feature works as intended)
• New and existing unit/integration tests pass locally with my changes
• Any dependent changes have corresponding PRs that are listed above