DC security analysis

[annetill]

Describe the current behavior

During the work on #927, we notice that:

• Some supported actions have no impact in DC calculation, but we simulate them (with no impact in theory). The good solution should be to drop them (ratio tap changer, shunt compensator, emulation AC (not supported in DC for the moment), etc. This should be analysed in detailed.
• In case of slack distribution failure, the behavior is not identical, an AC parameter has to be shared between AC and DC modes in order to throw or fail.

Describe the expected behavior

This should be done in another PRs.

Describe the steps

No response

Environment

No response

Relevant Log Output

No response

Extra Information

No response