refactor(datetime): remove usage of ion-buttons and Phosphor icons

[brandyscarney]

Issue number: N/A

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What is the current behavior?

The Datetime component breaks CSP rules due to the following:

1. Datetime is using ion-buttons which uses scoped encapsulation.
2. When using the ionic theme, it imports Phosphor icons as data URIs, which are blocked by connect-src 'self' blob:.

What is the new behavior?

• Remove all usages of ion-buttons, removing the dependency on a scoped component
• Remove all references to Phosphor icons
• Updates the styling to account for the removal of ion-buttons

Does this introduce a breaking change?

• [ ] Yes
• [x] No

Other information

All screenshot diffs are expected

• The majority are just rendering differences as I could not see any difference locally
• The ionic theme changes are due to the icon changing