Update WikiTest to prevent CSP warnings

[labkey-tchad]

Rationale

WikiTest.testEmbeddedVideoInWiki triggers a CSP warning. Now that frame-src is modifiable, the test should configure it to allow youtube embedding without triggering a warning.

The Table component is an absolute mess. Taking a small step forward by making it unnecessary to always specify which row contains the column headers. The row defaults to 1 and the dumbster email table sets it to 2. Tables with an actual thead element should set it to 0.
Note: This does not unify the methods that fetch column headers (getTableHeader* looks in thead vs getColumnHeaders which looks in tbody)

Related Pull Requests

• Make external source forms more testable platform#6403

Changes

• Test component for AdminController.ExternalSourceAction
• Update WikiTest.testEmbeddedVideoInWiki to customize frame-src CSP directive
• Update Table component to not pass header row index between methods