[New Feature] change from packageName to packagename

[Paul Williams]

Is your feature request related to a problem? Please describe.
When we have `packageName' as the name of a package then its not a java standard because it should essentially be all lower case however we have used camelCase.

Describe the solution you'd like

Step 1: change from packageName to packagename. Reference

Step 2: Update the templates

• hexagonal-spring-boot-java
• hexagonal-spring-boot-kotlin

Additional context
Don't forgot to update the documentation in the templates repositories