fix: change blockquotes and actions (m.emote) to not render as cursive

[itsmeeudrino]

Description

This PR removes italic fontStyle from BlockQuote and MessageTextBody (m.emote)

Fixes #2553

notes: i assume there's no other place in the source using italic (except for ReactPrism)

Type of change

• 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)
• This change requires a documentation update

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings

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[itsmeeudrino]

I have read the CLA Document and I hereby sign the CLA

[itsmeeudrino]

I have read the CLA Document and I hereby sign the CLA

[itsmeeudrino]

recheck

[kfiven]

recheck

[kfiven]

@itsmeeudrino Can you try to reopen the PR?