Rework Spring properties comments and generates comments in YAML configuration

[Aurélien Mino]

Following #1956 : correctly generate comment for Spring yaml configuration.
This will involve:

• determine where to add comment (line above, or inline)
• probably remove block property comments (they're not really used, and we can deal with simple comment associated with a property)
• make a pass on all modules to adjust spring comments to be compatible for both yaml and properties format

[Aurélien Mino]

Bounty claimed: https://opencollective.com/generator-jhipster/expenses/173497

[Pascal Grimaud]

@murdos : approved