`Contest Parameters` document type processing.

[Mr-Leshiy]

Summary

For the full voting experience with the Representatives and Delegations need to define a special document type as Contest Parameters with its own specific validation logic.

Description

• Define a new Rust type struct ContestParameters.
• Add a necessary methods to expose data according to the Contest Parameters document type. All these data should be taken from the payload. For the first version lets assume that the JSON payload would always has all necessary data we need.
  • contest timeline (start and end date).
  • election public key (???)

#[derive(serde::Deserialise)]
struct ContestPrarametersPayload {
   voting_start: chrono::Datetime<Utc>,
   voting_end: chrono::Datetime<Utc>,
   election_pk: String,
}

• Add a new ContestParametersRule with the corresponding CatalystSignedDocumentValidationRule trait implementation.
• Add a constructor

    pub async fn new<Provider>(
        doc: &CatalystSignedDocument,
        provider: &Provider,
    ) -> anyhow::Result<Self>
    where
        Provider: CatalystSignedDocumentProvider,
    {
        if doc.report().is_problematic() {
            anyhow::bail!("Provided document is not valid {:?}", doc.report())
        }
        anyhow::ensure!(
            doc.doc_type()? == &CONTEST_PARAMETERS,
            "Document must be Contest Ballot type"
        );
     // perform the same set of validation as for the `CatalystSignedDocumentValidationRule`
    ...
}

• Add a corresponding test cases