Linter rule @azure-tools/typespec-azure-core/casing-style is not accurate

[pshao25]

We have linter rule @azure-tools/typespec-azure-core/casing-style, which will raise warning for something like VirtualMachineScaleSetVM, capital V and capital M. We should modify this rule to pass such cases.

[markcowl]

@markcowl find duplicate issue

[markcowl]

• There are a set of known exceptions to the camelCase rule in Azure, we should exempt these statically from the camelCase rule.