Add Project info to the string representation of Contracts

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Describe the bug (current behaviour)
Currently the string representation of contract records is the prefix. "Contract", followed by the names of signatory partners of the contract.

To reproduce

1. go to https://daisy.lcsb.uni.lu
2. go to contracts search page and use the search string "University of Tübingen"
3. nearly a dozen contracts will be listed, all with the same string representation in their details page. This creates the problem of not being able to distinguish among contracts (with a certain institute) in contract select boxes throughout DAISY forms.

Expected behavior
Adding project information to the string represengtation should solve the problem.

Environment:

• Deployment: daisy.lcsb.uni.lu
• Version 1.1.0

Additional information (error logs, screenshots)