refactor: Consolidate donation modal code

[LeoBonjo]

Description

Refactor so that DonateModal is imported in DonationButton in order to consolidate and clean things up.

So sorry if this is a repeat pull request! @yontank may have already fixed it :)

[github-actions[bot]]

Preview: https://s3.amazonaws.com/noam-gaash.co.il/11961342132/open-bus/158/index.html Preview Storybook: https://s3.amazonaws.com/noam-gaash.co.il/11961342132/open-bus/158/storybook/index.html Test Report (if available): 'https://s3.amazonaws.com/noam-gaash.co.il/11961342132/open-bus/34ab461d92e7970d9c39104fda1298cefc5740c4/test-results/index.html'

[NoamGaash]

thank you very much for this effort! apologies if I missed some duplication