Add adapters to handle internal references in BlocksFields

[cekk]

This is needed to keep reference catalog updated also with contents that don't implement IBlocks behavior (on plone.restapi these adapters are registered only for this interface) but have BlocksFields

[coveralls]

Pull Request Test Coverage Report for Build 7869677472

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 63.854%

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Totals
Change from base Build 7757583307:	0.0%
Covered Lines:	855
Relevant Lines:	1339

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💛 - Coveralls