Feature: match postman-cli default when openapi definition does not include a server

[Tristano8]

Description

Matches the existing behaviour of postman-cli's 'Import from openapi' with a couple of defaults:

• uses {{baseUrl}} when no servers entry is found. This addresses [Feature] OpenAPI Import: make server protocol and host easily changeable #1239
• uses an empty string when info field is not present

Example result:

Contribution Checklist:

• The pull request only addresses one issue or adds one feature.
• The pull request does not introduce any breaking changes
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Note: Keeping the PR small and focused helps make it easier to review and merge. If you have multiple changes you want to make, please consider submitting them as separate pull requests.

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