[UI Enhancement] Updated left doc panel styling

[blindaa121]

Description

Preview: https://docusaurus-openapi-36b86--pr557-qp643zfx.web.app/petstore_versioned/add-pet

This PR consists of the following UI changes throughout the left doc panel with efforts to improve UI/UX, SEO, and LLMO (future application).

• Establish heading hierarchy for Requests and Responses to better distinguish separation, improve SEO/LLMO, and provide the ability to anchor to each section
• Removal of duplicate doc title heading
• Convert MethodEndpoint to header element to improve Algolia indexing
• Decreased font-size and applied uppercase text transformation for lower level headings (Request Params, Request Body, Schema)
• Use of var(--ifm-font-family-monospace) for property related items
• Updated Tabs styling for consistency throughout the doc page
• Response ApiTabs styling refresh
• Replace SchemaItem/ParamsItem hover-state background highlighting with property name highlighting
• Updated badge styling for required,nullable, and deprecated properties

Motivation and Context

Changes are made in efforts to improve UI/UX

Screenshots (if appropriate)

Types of changes

• New feature (non-breaking change which adds functionality)

Checklist

• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes if appropriate.
• All new and existing tests passed.

[github-actions]

Visit the preview URL for this PR (updated for commit 33aeed9):

https://docusaurus-openapi-36b86--pr557-qp643zfx.web.app

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[sserrata]

LGTM 👍🏽