Support folded style yaml configuration

[vsevel]

Description

Given an application.yaml and the following code:

    @ConfigProperty(name = "a.b.c.d")
    String prop;

I would like to be able to write:

a.b:
  c.d: Hello RESTEasy

or:

a.b.c.d: Hello RESTEasy

and not just the full hierarchy:

a:
  b:
    c:
      d: Hello RESTEasy

it makes it a lot easier to read and maintain.

another example:

quarkus:
  security.users.embedded:
    enabled: true
    plain-text: true
    users:
      scott: jb0ss
      stuart: test
      jdoe: p4ssw0rd
      noadmin: n0Adm1n
    roles:
      scott: Admin,admin,Tester,user
      stuart: admin,user
      jdoe: NoRolesUser
      noadmin: user

instead of:

quarkus:
  security:
    users:
      embedded:
        enabled: true
        plain-text: true
        users:
          scott: jb0ss
          stuart: test
          jdoe: p4ssw0rd
          noadmin: n0Adm1n
        roles:
          scott: Admin,admin,Tester,user
          stuart: admin,user
          jdoe: NoRolesUser
          noadmin: user

/cc @radcortez

Implementation ideas

No response

[famod]

/cc @radcortez

[radcortez]

Closing this one because I believe it is a duplicate of #11744. Please contribute there, or if you believe that is something different please reopen it again.