Add items to Component Registry test plan

[twagoo]

https://trac.clarin.eu/ticket/713

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Add to Component Registry test plan:

• download private profile XML + XSD as unauthenticated user
• verify expanded xml and xml downloads
• should NOT be allowed to user private components in a group component (see Trac #712)
• should NOT be allowed to move component with private component references to group (see Trac #712)
• should be allowed to use group components in a private component (see Trac #717)
• should be allowed to create a private copy of a group component with references to other group components (see Trac #717)

[twagoo]

Test plan currently implemented as google doc, see https://trac.clarin.eu/wiki/SoftwareTesting#Testplans