fix: support path level parameters for open_api_spec_parser

[jeffreyrubi]

Adding support of path level parameters in open_api_spec_parser as defined in the OpenAPI spec.
Ref: https://swagger.io/docs/specification/v3_0/describing-parameters/#common-parameters

This PR aimed in fixing #540 (*detailed problem description)

What this PR does

• Append path-level parameters to all HTTP methods under the path operator as defined in OpenAPI spec.
• Unittest to ensure it works as expected.

Proof that it works

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