feat: clearer backup and restore info

[rolznz]

Fixes #645

Adds a link to our guide, makes copy on the backup and seed imports more clear and warns against importing from seed if you have open channels

[rolznz]

Addressed feedback:

• More clear text in second checkbox on backup page, now also only shows when first checkbox is checked
• Added checkbox on import page

[jpl-btc]

Alternative copy for the 3 warning sentences (feel free to use/remix/not use):

• Your recovery phrase is a set of 12 words used to restore your savings balance from a backup.

• Keep it safe and private to ensure your funds remain secure.

• Please note, the recovery phrase cannot restore funds from lightning channels. If you had active channels on a different device, contact Alby support before proceeding. (note: the red color is not eye friendly and I have encountered colorblind users that had to select the text with the mouse to be able to read it, this happens also when setting up the unlock password)

[rolznz]

@jpl-btc thanks for the feedback. Updated the copy and removed the red styling on the pages. The setup password second confirmation checkbox has bold text which differentiates it from the first confirmation box anyway, I think that's enough (and the destructive style was a bit buggy on the checkbox anyway because I couldn't find a way to change the fill color on the checkbox. CC @reneaaron )