This endpoint serves two different underlying objects and picks the flow automatically from the
caller's identity: Salesforce-authenticated callers get Salesforce email templates
(APXTConga4__Conga_Email_Template__c), everyone else gets platform email templates.

Because the two objects do not share searchable fields, every searchBy option is prefixed
with the flow it belongs to:

• Default - available to both. Uses Salesforce_Name for Salesforce callers and Platform_AccessType for platform callers.
• Salesforce_Name - SALESFORCE ONLY. Matches searchValue against the Conga template name (APXTConga4__Name__c).
• Salesforce_Description - SALESFORCE ONLY. Matches searchValue against the description (APXTConga4__Description__c).
• Salesforce_TemplateGroup - SALESFORCE ONLY. Matches searchValue against the template group (APXTConga4__Template_Group__c).
• Salesforce_All - SALESFORCE ONLY. Matches searchValue across the Conga template name, description and template group (APXTConga4__Name__c, APXTConga4__Description__c, APXTConga4__Template_Group__c); a template is returned if searchValue matches any of the three.
• Platform_AccessType - PLATFORM ONLY. Matches searchValue against the access type, for example "private" or "public".
• Platform_CategoryId - PLATFORM ONLY. Matches searchValue against the email template category id.

Choosing an option that does not belong to the caller's flow returns 400 instead of silently
ignoring the filter.

When searchValue is omitted the behaviour is source-specific:

• Salesforce callers - no search filter is applied and all Conga email templates are returned.
• Platform callers - the downstream email API is called with its default access-type filter
  (searchBy=AccessType&searchValue=private), so only private platform templates are returned.
  Pass searchBy=Platform_AccessType with an explicit searchValue (for example "public")
  to override that default.