Rao parameters separate unit from objective function type

[pjeanmarie]

Please check if the PR fulfills these requirements

• The commit message follows our guidelines
• 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?

#1084

What kind of change does this PR introduce?

What is the current behavior?

What is the new behavior (if this is a feature change)?

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

• Yes
• No

If yes, please check if the following requirements are fulfilled

• 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)

    if "type" in obj_fun:
        if "MAX_MIN_MARGIN" in obj_fun["type"]:
            new_obj_fun["type"] = "MAX_MIN_MARGIN"
        elif "MAX_MIN_RELATIVE_MARGIN" in obj_fun["type"]:
            new_obj_fun["type"] = "MAX_MIN_RELATIVE_MARGIN"
        if "MEGAWATT" in obj_fun["type"]:
            new_obj_fun["unit"] = "MW"
        elif "AMPERE" in obj_fun["type"]:
            new_obj_fun["unit"] = "A"

Other information:

[obrix]

Small comment on deserialization of unit, it may be simplified.