Improvements on French language file

[ici-be]

Description

Improvements on French language file

Issues

• part of fix Some remaining translation to do #3002
• ...

Please check if the PR fulfills these requirements

• The commit message follows our guidelines: https://github.com/geosolutions-it/MapStore2/blob/master/CONTRIBUTING.md
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

What kind of change does this PR introduce? (check one with "x", remove the others)

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Other... Please describe:

What is the current behavior? (You can also link to an open issue here)

What is the new behavior?

Does this PR introduce a breaking change? (check one with "x", remove the other)

• Yes
• No

If this PR contains a breaking change, please describe the impact and migration path for existing applications: ...

Other information:

[mbarto]

Thanks for the contribution!

[coveralls]

Coverage decreased (-0.03%) to 80.893% when pulling 319627f on BUP-Brussels:master into 013d559 on geosolutions-it:master.

[MV88]

Actually i'm not sure that if fixes the #3002