fix(wallet): implement DApps decrypt screen (uplift to 1.40.x)

[Pavneet-Sing]

Uplift of #13868
Resolves brave/brave-browser#23260

Pre-approval checklist:

• You have tested your change on Nightly.
• This contains text which needs to be translated.
  • There are more than 7 days before the release.
  • I've notified folks in #l10n on Slack that translations are needed.
• The PR milestones match the branch they are landing to.

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Post-merge checklist:

• The associated issue milestone is set to the smallest version that the changes is landed on.

[kjozwiak]

Closing as there's no 1.40.x maintenance release for this cycle so we'll basically only be doing chromium bumps and HF (hotfixes) if needed. With HF releases, we only include critical fixes rather than additions/new features. The above is a substantial change so we'll let it ride via 1.41.x.