hocon: fix round-tripping of extraneous comment indent

[jpenilla]

fixes https://github.com/Hexaoxide/Carbon/issues/311 properly

[zml2008]

This looks like it should be a good improvement, what are you thinking still needs to happen before this is undrafted?

[jpenilla]

Probably could have undrafted it earlier, rebased now though

Is it intentional that -vendor tests don't run on ci? I checked that typesafe-configs passed locally fwiw

[zml2008]

That is not intentional I don't think, could use a test task in the root project that depends on the test tasks in the included vendor build