Auto install ethereum-remote-client and add for usage on first access of brave://wallet

[bbondy]

task manager should not show the process until you load brave://wallet.
The extension dir should not exist until after first load of the wallet: ~/Library/Application\ Support/BraveSoftware/Brave-Browser-Development/odbfpeeihdkbihmopkbjmoonfanlbfcl

[kjozwiak]

Verification PASSED on macOS 10.14.6 x64 using the following build:

Brave	0.69.129 Chromium: 77.0.3865.90 (Official Build) (64-bit)
Revision	58c425ba843df2918d9d4b409331972646c393dd-refs/branch-heads/3865@{#830}
OS	macOS Version 10.14.6 (Build 18G95)

• ensured that launching brave for the first time doesn't have the Extensions: Crypto Wallets process running via the Task Manager
• ensured that odbfpeeihdkbihmopkbjmoonfanlbfcl isn't being created in a new profile unless opening brave://wallet for the first time
• ensured that once brave://wallet is opened, the Extensions: Crypto Wallets process is visible via the Task Manager

Verification passed on

Brave	0.69.129 Chromium: 77.0.3865.90 (Official Build) (64-bit)
Revision	58c425ba843df2918d9d4b409331972646c393dd-refs/branch-heads/3865@{#830}
OS	Windows 10 OS Version 1803 (Build 17134.1006)

• ensured that launching brave for the first time doesn't have the Extensions: Crypto Wallets process running via the Task Manager
• ensured that odbfpeeihdkbihmopkbjmoonfanlbfcl isn't being created in a new profile unless opening brave://wallet for the first time
• ensured that once brave://wallet is opened, the Extensions: Crypto Wallets process is visible via the Task Manager

Verification passed on

Brave	0.69.129 Chromium: 77.0.3865.90 (Official Build) (64-bit)
Revision	58c425ba843df2918d9d4b409331972646c393dd-refs/branch-heads/3865@{#830}
OS	Ubuntu 18.04 LTS

• ensured that launching brave for the first time doesn't have the Extensions: Crypto Wallets process running via the Task Manager
  

• ensured that odbfpeeihdkbihmopkbjmoonfanlbfcl isn't being created in a new profile unless opening brave://wallet for the first time

• ensured that once brave://wallet is opened, the Extensions: Crypto Wallets process is visible via the Task Manager