Prevent a template from being deleted if it is in use

[netwolfuk]

Expected Behaviour

• Should not be ale to delete a template, if there is a webhook using it.

Current Behaviour

• Template can be deleted with no checks.

[netwolfuk]

Create WebHook settings manager which provides the following.

1. CRUD webhooks via this manager.
2. Ability to find all webhooks (grouped by project tree somehow).
3. Ability to find webhooks by project, buildEvent, buildType, templateId, tag (see Add a label to webhook configuration #116), authType.
4. Ability to find webhooks by url (substring).
5. Ability to find only enabled webhooks along with above filters. Eg, show me webhooks that will actually fire for this specific buildType.
6. "full text search" eg, just start typing and it will find any matching webhooks. Should search tags, url, buildTypeName, buildTypeExternalId, projectName, projectExternalId. These could be "tags" and "url" and could be cached.
7. Quick (cached) results for count of webhooks, by project, by template, etc. These should be updated on each webhook write (async).

Returned results should include the following so that they can be displayed in UI:

1. match reason(s).
2. events enabled
3. buildTypes enabled
4. tags
5. url
6. template-id

Clicking a webhook should allow direct editing, not via some page when then requires finding and clicking again.

[netwolfuk]

Item 3 is not done yet.

[netwolfuk]

This is available for testing in the v1.2.0-alpha.3 release.