[dnm] acceptance tests for configuration #245

[bollwyvl]

References

• meant to be upstreamed into Language server configuration using the Advanced Settings Editor #245 (thanks @trajamsmith!)
• tests yaml-language-server Schema Support #244 (and therefore Language Server Configuration UI #196)

Code changes

• Adds some minimal schema as discussed
• adds a yaml fixture as suggested on Language server configuration using the Advanced Settings Editor #245
• reworks some keywords to be more reusable (more could be done, but 🤷)
• adds a (failing) acceptance test with a few TODOs

User-facing changes

None

Backwards-incompatible changes

None

Chores

• linted
• tested
• documented
• changelog entry

[bollwyvl]

Looks like #245 is well on its way at this point!