Display warning for confidential epic

Create epic warning component

Create epicWarning component and
modify commentForm to conditionally display issueWarning

Add locale string for confidential epic warning

Rename to epic

Add spec for epicWarning

Rename isIssuableType to isIssueType

Refactor epicWarning

Add snapshot for epicWarning spec

Add changelog entry

Apply 1 suggestion(s) to 1 file(s)

Use GlIcon instead of Icon

Add test for when noteable is not epic