feat: 942 - new methods updatePrice, updateProof; new proof parameters

[monsieurtanuki]

What

• New Prices methods updatePrice and updateProof
• New parameters for uploadProof, getPrices and getProofs

Fixes bug(s)

• Closes: #942

Files

New files:

• update_price_parameters.dart: Parameters for the "update price" API query.
• update_proof_parameters.dart: Parameters for the "update proof" API query.

Impacted files:

• api_prices_test.dart: added tests for updatePrice and updateProof; refactored the access to uriHelper
• get_prices_parameters.dart: added 2 parameters for getPrices queries
• get_proofs_parameters.dart: added 9 parameters for getProofs queries
• http_helper.dart: minor refactoring for PATCH queries in Prices
• open_prices_api_client.dart: new methods updatePrice and updateProof; new parameters for uploadProof; refactored createPrice
• openfoodfacts.dart: added the new 2 files
• price.dart: added field updated
• price.g.dart: generated
• proof.dart: added fields locationOSMId, locationOSMType, locationId, date, currency, updated and location
• proof.g.dart: generated

[monsieurtanuki]

Thank you @teolemon for your review!