Linter: add pattern as addidional config in StandardNamingConfig

[linupi]

I am trying to use LinkML in the context of an already existing project where I don't have the liberty to alter the naming convention for slots and classes. In order to still be able to use the linter I would need to have a more flexibility in the standard_naming rule.

There are two independent features that I'd like to propose:

1. allow the lowerCamelCase naming convention
2. add class_pattern and slot_pattern as additional, optional configuration in the standard_naming linter rule

How important is this feature? • Medium - can do work without it; but it's important (without this change I won't be able to use the linter)

When will use cases depending on this become relevant? • Short-term - 2-4 weeks