wallet age verification -> modify to let multiples chains been choosen at the same verification

[stefi-says]

The wallet age verification was implemented on issue #10. From there the possibility to let the user check multiple chains to get the wallet age seems important.

Develop that so:

• change the :
  chainName = st.selectbox('Select the chain you would like to check the walle', covalent_chains)
  to a multiple selection option wiget and addapt the code to support at least 2 possibles chains.

BUT FIRST -.> CHECK USERS IMPUT TO PRIORITIZE THIS ISSUE
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