feat: support newlines in headers, params, and variables

[pooja-bruno]

Description

This PR adds support for newlines in header names, query parameter names, and variable names in Bruno's .bru file format.

JIRA

Contribution Checklist:

• [x] The pull request only addresses one issue or adds one feature.
• [x] The pull request does not introduce any breaking changes
• [x] I have added screenshots or gifs to help explain the change if applicable.
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[sid-bruno]

can we also add in tests for bruToJson and jsonToBru for the multiline checks to keep things reliable