Reset skus from brave://skus-internals

[simonhong]

Add reset button brave://skus-internals and reset skus state from local state

When reset button is pressed, skus.state should be reverted to default.

[stephendonner]

Verification PASSED using

Brave	1.53.50 Chromium: 114.0.5735.26 (Official Build) nightly (x86_64)
Revision	7075cbb66f0542ac3e01ddfde6b813e7d61118a5-refs/branch-heads/5735@{#454}
OS	macOS Version 13.4 (Build 22F66)

Steps:

1. installed 1.53.50
2. launched Brave
3. purchased, configured, and connected to Brave VPN using account.bravesoftware.com (staging)
4. opened brave://skus-internals
5. clicked on Fetch SKUs state
6. confirmed JSON nested-tree blob
7. disconnected from Brave VPN
8. clicked on Reset SKUs state
9. confirmed was prompted to confirm, with warning
10. clicked OK
11. confirmed JSON view was cleared of its values (but still had its top-level fields)
12. waited some time for VPN-session credentials to time out/expire
13. clicked on the VPN button in the toolbar

Confirmed my credentials were wiped, and I was presented with the Buy/Already purchased VPN? dialog

example	example	example	example	example	example

[kjozwiak]

The above needs to be re-verified due to brave/brave-core#18356, brave/brave-core#18403 & brave/brave-core#18527 being uplifted into 1.52.x via brave/brave-core#18538. Used #30191 (comment) as the needed verification on Nightly to uplift into 1.52.x as per brave/brave-core#18538 (review).

[stephendonner]

Verification PASSED using

Brave	1.52.112 Chromium: 114.0.5735.35 (Official Build) (x86_64)
Revision	2295354895fa3652ae47b651481831484f16d1ff-refs/branch-heads/5735@{#713}
OS	macOS Version 13.5 (Build 22G5027e)

Steps:

1. installed 1.52.112
2. launched Brave
3. purchased, configured, and connected to Brave VPN using account.bravesoftware.com (staging)
4. opened brave://skus-internals
5. clicked on Fetch SKUs state
6. confirmed JSON nested-tree blob
7. disconnected from Brave VPN
8. clicked on Reset SKUs state
9. confirmed was prompted to confirm, with warning
10. clicked OK
11. confirmed JSON view was cleared of its values (but still had its top-level fields)
12. waited some time for VPN-session credentials to time out/expire
13. clicked on the VPN button in the toolbar

Confirmed my credentials were wiped, and I was presented with the Buy/Already purchased VPN? dialog

example	example	example	example	example	example