Normalize Older ARM TypeSpec

[markcowl]

TypeSpec that was created before MPG often follows patterns that work in OpenAPI, but not in generated clients. We need a plan to fix these specs. Some sample issues include:

• Specs that rely on implicitOptionality for PATCH requests
• Specs with custom lros that do not correctly model the finalResult
• Specs that use OpenAPI decorators
• Specs in the RPSaaSMaster repo exclusion list for TypeSpec validation

Set up a plan for identifying these issues and verifying the suitability of these specs for MPG and other emitters.