Replace contingencyId by contingencyIds for ContingencyContext

[EtienneLt]

Please check if the PR fulfills these requirements

• [x] The commit message follows our guidelines
• [x] Tests for the changes have been added (for bug fixes / features)
• [ ] Docs have been added / updated (for bug fixes / features)

Does this PR already have an issue describing the problem? No

What kind of change does this PR introduce? Feature

What is the new behavior (if this is a feature change)? Contingency context can now reference several contingencies.

Does this PR introduce a breaking change or deprecate an API?

• [X] Yes
• [ ] No

If yes, please check if the following requirements are fulfilled

• [X] The Breaking Change or Deprecated label has been added
• [ ] The migration steps are described in the following section

What changes might users need to make in their application due to this PR? (migration steps)

• ContingencyContext.getContingencyId() returning a unique String was replaced by ContingencyContext.getContingencyIds() returning a list of Strings.

• An exception is now thrown when a ContigencyContext has contingency ids but is not declared of SPECIFIC type. Previously it was ambiguous as it could be either interpreted as a specific contingency context or as one of the declared type.

[sonarqubecloud[bot]]

Quality Gate passed

Issues
2 New issues
0 Accepted issues

Measures
0 Security Hotspots
83.7% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[sonarqubecloud[bot]]

Quality Gate passed

Issues
1 New issue
0 Accepted issues

Measures
0 Security Hotspots
83.7% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud