Allow configuration of annotation processing

We should allow the configuration of annotation processing via MP Config, for example, which packages to scan (improves performance for large apps).

For example, a dev should be able to do this inside META-INF/microprofile-config.properties

openapi.packagesToScan=abc,def,
openapi.server=myhost:8443
...
openapi.filter=mypackage.myFilter  

The implementation of this spec would get those values injected (or can manually query for them).

[leochr]

Latest list of configurable properties:

• mp.openapi.model.reader Configuration property to specify the fully qualified name of the OASModelReader implementation.

• mp.openapi.filter Configuration property to specify the fully qualified name of the OASFilter implementation.

• mp.openapi.scan.disable Configuration property to disable annotation scanning.

• mp.openapi.scan.packages Configuration property to specify the list of packages to scan.

• mp.openapi.scan.classes Configuration property to specify the list of classes to scan.

• mp.openapi.servers Configuration property to specify the list of global servers that provide connectivity information.

• mp.openapi.servers.path. Prefix of the configuration property to specify an alternative list of servers to service all operations in a path.

• mp.openapi.servers.operation. Prefix of the configuration property to specify an alternative list of servers to service an operation.

• mp.openapi.extensions. Recommended prefix for vendor specific configuration properties.

[pilhuhn]

Perfectly fine with me 😃 I think it should be consistent with other specs. I have created a thread in the Google group at https://groups.google.com/forum/?utm_medium=email&utm_source=footer#!topic/microprofile/LujyD0OYrP0