Wallet transactions: show exact time as tooltip when hovering on the relative time ago

[tredondo]

Description

In the wallet transactions, the time is only given approximately, e.g."1m" or "8h". It's customary to show the exact time when mousing over such labels.

Steps to Reproduce

1. Find a transaction in your wallet
2. Mouse over its timestamp

Expected result:

Brave version (brave://version info)

Brave	1.32.113 Chromium: 96.0.4664.45 (Official Build) (64-bit)
Revision	76e4c1bb2ab4671b8beba3444e61c0f17584b2fc-refs/branch-heads/4664@{#947}
OS	Linux

Version/Channel Information:

Version 1.32.113 Chromium: 96.0.4664.45 (Official Build) (64-bit)

[srirambv]

Brave	1.35.93 Chromium: 97.0.4692.71 (Official Build) beta (64-bit)
Revision	adefa7837d02a07a604c1e6eff0b3a09422ab88d-refs/branch-heads/4692@{#1247}
OS	☑️ Linux	☑️ Windows 11 Version Dev (Build 22523.1000)	☑️ macOS Version 12.0.1 (Build 21C52)
Verified tooltip shows exact transaction time when hovered over Encountered #20774
Max window screen
Default browser window size
Min width window size