[DEV-3019] Remove type assertion and redundant filter

[Sebastiano-Bertolin]

List of Changes

Remove redundant filter
Add type check function for MarkDownPart
Remove type assertion

Motivation and Context

Improve code efficiency and readability

How Has This Been Tested?

Manually

Screenshots (if appropriate):

Types of changes

• Chore (nothing changes by a user perspective)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly.

[changeset-bot]

🦋 Changeset detected

Latest commit: 66ddfac

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
nextjs-website	Patch

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[github-actions]

Jira Pull Request Link

This Pull Request refers to the following Jira issue DEV-3019