Only show MM/crypto wallets import flow when the user has actually created a wallet on MM/crypto wallets

[srirambv]

Description

Current flow detects installation of MM and prompts to import on the new wallet screen. This fails as there is nothing to import so seems unnecessary to show the Import from MM button and the importer page

Steps to Reproduce

1. Install MM from Web Store (do not create an account)
2. Enable flag and enable wallet
3. Wallet page shows Import from MM even when there is nothing to import from

Actual result:

Wallet page shows Import from MM even when there is nothing to import from

Expected result:

Only show MM import button when the user has actually created a wallet on MM

Reproduces how often:

Easy

Brave version (brave://version info)

Brave	1.32.38 Chromium: 94.0.4606.71 (Official Build) nightly (x86_64)
Revision	1d32b169326531e600d836bd395efc1b53d0f6ef-refs/branch-heads/4606@{#1256}
OS	All

Version/Channel Information:

• Can you reproduce this issue with the current release? NA
• Can you reproduce this issue with the beta channel? NA
• Can you reproduce this issue with the nightly channel? Yes

Other Additional Information:

• Does the issue resolve itself when disabling Brave Shields? NA
• Does the issue resolve itself when disabling Brave Rewards? NA
• Is the issue reproducible on the latest version of Chrome? NA

Miscellaneous Information:

@darkdh @jamesmudgett

[darkdh]

This should also applies to crypto wallets.
Don't show import flow when we detect crypto wallets is not setup

[srirambv]

Brave	1.35.98 Chromium: 98.0.4758.72 (Official Build) (64-bit)
Revision	d0fe1ec4df090cd3eb02b591228505e12ea476e9-refs/branch-heads/4758@{#935}
OS	☑️ Linux	☑️ Windows 11 Version Dev (Build 22523.1000)	☑️ macOS Version 12.0.1 (Build 21C52)
Verified steps from brave/brave-core#11354 Verified when CW Extension is installed, no importer is shown Verified when CW Extension is installed and wallet is created, importer is shown during onboarding Encountered #20799
	18534-Linux.mp4	18534-Windows.mp4	18534-macOS.mp4