Allow event outcome to be blank

[lorawoodford]

Description

Fixes linked record and Events > Browse views to account for event outcomes that are blank/NULL. Added a ternary in the impacted views to confirm that a record['outcome'] exists before attempting to display the translation for that outcome value in the table. Additionally, I confirmed by pulling records out via the API that, when an outcome is not present in a record, the outcome key does not exist (e.g. it's just not there, not it's there but is blank).

Related JIRA Ticket or GitHub Issue

Partial fix for: https://archivesspace.atlassian.net/browse/ANW-778

Motivation and Context

An outcome is not a required field for an event record, so the outcome column in the staff UI should not assume that there will always be a value to display.

How Has This Been Tested?

Backend tests passed looked, inspected visually on a local branch.

Screenshots (if appropriate):

Before change:

After change:

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.