Improve Mnemonic handling + UX, Add Advanced Mode

[JSKitty]

Abstract

This PR largely improves Seed Phrase UX, by:

• Simplifying the Creation and Import flows (Resolves Create / Import Wallet potential issue with new BIP39 pw field #117).
• Improving validation robustness (whitespace handling, less generic errors).

The UX is simplified by removing the below functionality, outside of "Advanced Mode":

• Hiding the "Optional Passphrase (BIP39)" from the New Wallet 'wizard'.
• Hiding the "Optional Passphrase (BIP39)" from the "Import Wallet" flow.
• Removing the "Are you sure?" popup on typo'd seeds, strictly denying their import.

"Advanced Mode" is an off-by-default, session persisted mode in which MPW's functionality is simplified, to improve the experience for less knowledgeable users that are prone to losing funds from accidental mistakes, such as mixing up BIP39 Passphrases with their MPW Password, hitting "Confirm" when MPW warns of Seed Phrase typos, etc.

In future PRs, Advanced Mode will be leveraged to also hide features such as "VanityGen", and any other non-primary features of MPW, to simplify the app as much as possible for the average user.

This feature allows for both New and Advanced users to benefit from MPW, without any drawbacks, both communities can eat their cake, rather than removing "complex" features in the name of simplicity, but denying advanced users their tools.

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Testing

This PR can be tested in various ways, I'll outline a bunch of them below, each with their own "testing flow", feel free to try variations of these to maximise our testing reach!

1: Test Creating a new wallet in Normal and Advanced mode

• (Optional) visit Settings and enable "Advanced Mode" in the Wallet options.
• Visit Dashboard and Create a New Wallet.
• • If "Advanced Mode" is enabled, you'll see "Optional Passphrase" reveal itself.
• • If "Advanced Mode" is disabled, you should not see the "Optional Passphrase".

2: Test importing a Seed Phrase in various ways, in Normal or Advanced Mode

• (Optional) visit Settings and enable "Advanced Mode" in the Wallet options.
• Visit Dashboard and then "Access Wallet".
• • If "Advanced Mode" is enabled, when typing your Seed Phrase, you'll see the "Optional Passphrase" reveal itself.
• • If "Advanced Mode" is disabled, when typing your Seed Phrase, you should not see the "Optional Passphrase".

Now, try importing it in various ways, such as:

• • Import it as normal (all should go well).
• • Import it with a typo (with Advanced Mode, it will show a "confirm" popup, in Normal Mode, it will reject the typo entirely).
• • Import it with excess spaces at the start, end, or between existing words. (It should ignore the spaces, and if they break the words, it will reject the import).

If any errors are found, the PR works unexpectedly, or you have viable suggestions to improve the UX or functionality of the PR, let me know!

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[floki008]

tack: tested on linux different inputs:
1- valid seedphrase passed
2- non-valid seedphrase was blocked
3- valid seedphrase with white spaces was stripped as expected

[Duddino]

The PR works really well, i tried inserting a number of spaces in various places of the seed phrase and they all got removed as expected.
I've left some minors nitpicks

[Duddino]

tACK