Use generator local targetV if set as locale regulation

[vidaldid-rte]

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)
• A PR or issue has been opened in all impacted repositories (if any)

Does this PR already have an issue describing the problem?
#1268

NOTE:
This PR depends on powsybl/powsybl-core#3635 (review)

**What kind of change does this PR introduce?**
If a generator is configured for remote voltage control but needs to turn local for any reason and if a local target v is defined, that value is used instead of keeping the same pu target.
Reasons for tunring remote to local include:
    parameter voltageRemoteControl set to false
    consistency checks in OLF that switch a remote voltage control to a local voltage control 



**What is the current behavior?**
When a generator is moved to local voltage control the remote target in pu is kept locally



**What is the new behavior (if this is a feature change)?**
If a local target has been defined (by a state esimator or any other process in charge of coputing voltage target) that value is used instead.



**Does this PR introduce a breaking change or deprecate an API?**
- [ ] Yes
- [X] No - but it takes advantage of a new API in core that may be a simple addition to existing APIs or be embedded in a breaking change refactoring in core