UI: Decrypt asym. encr. channel data

[dominic22]

For asym. encr. channels, the channel data can't be decrypted by the IS thus the UI needs to give this option to the user.

• add decryption button which let's you insert your private key to create the shared key using the private key and the public key inside the channel info (insert document as when logging in or by inputting into text field)
• hide decryption button if the channel is not a privateplus channel
• store this shared key in the browsers pw manager or in the state so the user doesn't need to input the private key whenever it reads/writes data.
• investigate if storing in browser pw manager has better ux or temporary state.
• store channel id together with asymSharedKey to check whether we need to display the unlock component or not
• Send stored asym shared key with request

reuse input of file from Verify a credential or Identity login

[dominic22]

@JuriBog Please also add privatePlus channel type to the is-ui-components so it can be selected when creating a channel.