feat: add custom icon to accordian header

[RuliSlim]

Description

Related issue(s)

What kind of change does this PR introduce? (check at least one)

• Bug fix (non-breaking change which fixes an issue)
• New Feature (non-breaking change which adds functionality)
• New Feature (BREAKING CHANGE which adds functionality)
• Refactor
• Build-related changes
• Other, please describe:

Does this PR introduce a breaking change? (check one)

• Yes
• No

If yes, please describe the impact and migration path for existing applications:

How has this been tested?

Screenshots (if appropriate):

The PR fulfils these requirements:

• It's submitted to the main branch
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• My change requires a change to the documentation. (Managed by Tremor Team)
• I have added tests to cover my changes
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Name	Status	Preview	Comments	Updated (UTC)
tremor-storybook	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Jan 5, 2024 8:37am

[severinlandolt]

Hi @RuliSlim, thank you for taking your time and creating this PR, but I have to say no to this. There aren't any issues asking for this feature plus would it lead to inconsistencies across the library where icons are used.