User wallet: Add fund flow

[mandar-brave]

Old add funds flow needs to go.
Only users with Uphold wallets can add funds.
Add funds is handed off to Uphold for managing transfers in initial release

@NejcZdovc
@jenn-rhim for UI/UX changes.
cc @alexwykoff

[mandar-brave]

For Add-funds, the link should take user to Uphold site with the right URL to allow user to add funds on Uphold site
For With-funds, the link should take user to Uphold account

[LaurenWags]

Verified passed with

Brave	0.69.121 Chromium: 76.0.3809.132 (Official Build) beta (64-bit)
Revision	fd1acc410994a7a68ac25bc77513d443f3130860-refs/branch-heads/3809@{#1035}
OS	Mac OS X

• Verified test plan from Uphold wallet brave-core#2696

• Verified if you've never connected an uphold account, Add Funds and Withdraw Funds take you to onboarding modal
  

• Verified if you connect an account that is not KYC'd, and you click on Add Funds, you are taken to your Add Funds page for your Brave Browser Card (note - without KYC not all options will be available to the user)
  

• Verified if you connect an account that is not KYC'd and you click on Withdraw Funds, you are taken to a page to complete KYC
  

• Verified if you connect a KYC'd Uphold account and click on Add Funds, you are taken to your Add Funds page for your Brave Browser Card
  

• Verified if you connect a KYC'd Uphold account and click on Withdraw Funds, you are taken to the 'Use Funds' page for your Brave Browser card:
  

Verification passed on

Brave	0.69.123 Chromium: 76.0.3809.132 (Official Build) beta (64-bit)
Revision	fd1acc410994a7a68ac25bc77513d443f3130860-refs/branch-heads/3809@{#1035}
OS	Ubuntu 18.04 LTS

• Verified test plan from Uphold wallet brave-core#2696

• Verified if you've never connected an uphold account, Add Funds and Withdraw Funds take you to onboarding modal
  

• Verified if you connect an account that is not KYC'd, and you click on Add Funds, you are taken to your Add Funds page for your Brave Browser Card (note - without KYC not all options will be available to the user)
  

• Verified if you connect an account that is not KYC'd and you click on Withdraw Funds, you are taken to a page to complete KYC
  

• Verified if you connect a KYC'd Uphold account and click on Add Funds, you are taken to your Add Funds page for your Brave Browser Card
  

• Verified if you connect a KYC'd Uphold account and click on Withdraw Funds, you are taken to the 'Use Funds' page for your Brave Browser card:
  

Verification passed on

Brave	0.70.93 Chromium: 76.0.3809.132 (Official Build) beta (64-bit)
Revision	fd1acc410994a7a68ac25bc77513d443f3130860-refs/branch-heads/3809@{#1035}
OS	Windows 10 OS Version 1803 (Build 17134.1006)

• Verified test plan from Uphold wallet brave-core#2696
• Verified if you've never connected an uphold account, Add Funds and Withdraw Funds take you to onboarding modal

• Verified if you connect an account that is not KYC'd, and you click on Add Funds, you are taken to your Add Funds page for your Brave Browser Card (note - without KYC not all options will be available to the user)

• Verified if you connect an account that is not KYC'd and you click on Withdraw Funds, you are taken to a page to complete KYC

• Verified if you connect a KYC'd Uphold account and click on Withdraw Funds, you are taken to the 'Use Funds' page for your Brave Browser card: