imp(str-v2): Add Event after successful ERC20 extension registration

[Vvaradinov]

Description

This PR adds an event after successful ERC20 extension registration.

Closes: #XXXX

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[MalteHerrmann]

LGTM! Thanks for adding @Vvaradinov - would love to see a test for this though :)

[MalteHerrmann]

Thanks for adding the test! 🙏 there are some print statements left that can probably be removed but other than that looks great 🚀