Do not parse JSON files in wallet component if wallet isn't created

[yrliou]

As this affects everyone's startup performance.

As investigated in a thread we parse the Wallet component even if there is no wallet created.

• no wallet created => no startup work to read/parse json
• (the best option) don't even register the component. This could create extra slow down on the first load, need to check.
• add a (browser) test to verify that to prevent future regression.

[bbondy]

Maybe do this by not even getting the component until a wallet is being created? I'm pretty sure we did this for Android at least recently cc @SergeyZhukovsky

[SergeyZhukovsky]

Yeah @AlexeyBarabash made it happen(download component on demand only) on Android in that PR brave/brave-core#19086. The main goal for Android was to not occupy space on devices unless wallet is created. The code could be re-used to share it with desktop as Java handlers got triggered from c++ code anyways.

[srirambv]

Verification passed on

Brave	1.62.99 Chromium: 120.0.6099.62 (Official Build) beta (64-bit)
Revision	0f3e892de210168e788b3418961f94c4d0c5942a
OS	Windows 11 Version 22H2 (Build 22621.2792)

• Verified steps from brave/brave-core#20741
• Verified wallet component is only downloaded after the wallet is created
• Verified when wallet component is being downloaded loading state is shown

Clean Install	MM Import	Brave Wallet Import
33757-Clean.Wallet.mp4	33757-MM.Import.mp4	33757-Import.Wallet.mp4

[srirambv]

Verification passed on Google Pixel 8 with Android 14 running 1.62.114 x64 Beta build

• Verified steps from brave/brave-core#20741
• Verified wallet component is only downloaded after the wallet is created
• Verified when wallet component is being downloaded loading state is shown