HangWatcher to nightly 50%

[atuchin-m]

Nightly 50%, tested manually.
Security review: brave/security#659

What the study does?

• enables sending crash dumps if a hang happens. The logic of hang detections are chromium and already works everywhere, but record only UMA.

What can go wrong? Is data loss possible?

• A lot of dumps because a lot of hangs or false positives.

min_version is set to current nightly with landed brave/brave-browser#19822
(the changed description in the settings page).

PRs to master:
#192
#193

The root issue:
brave/brave-browser#20304

[kjozwiak]

Verification PASSED on Win 11 x64 using the following builds:

Brave | 1.36.22 Chromium: 97.0.4692.71 (Official Build) nightly (64-bit)
-- | --
Revision | adefa7837d02a07a604c1e6eff0b3a09422ab88d-refs/branch-heads/4692@{#1247}
OS | Windows 11 Version 21H2 (Build 22000.376)

Brave | 1.35.75 Chromium: 97.0.4692.71 (Official Build) beta (64-bit)
-- | --
Revision | adefa7837d02a07a604c1e6eff0b3a09422ab88d-refs/branch-heads/4692@{#1247}
OS | Windows 11 Version 21H2 (Build 22000.376)

Brave | 1.34.80 Chromium: 97.0.4692.71 (Official Build) (64-bit)
-- | --
Revision | adefa7837d02a07a604c1e6eff0b3a09422ab88d-refs/branch-heads/4692@{#1247}
OS | Windows 11 Version 21H2 (Build 22000.376)

STR/Cases:

• ensured that both HangWatcher:HangWatcherEnableDumps & HangWatcher:Default are being used under Nightly
• ensured that both HangWatcher:HangWatcherEnableDumps & HangWatcher:Default are not being used under Beta & Release

Nightly Enabled	Nightly Disabled

[kjozwiak]

Uplift into production for Nightly at 50% approved after deliberating with @brave/uplift-approvers. QA has verified the PR on Nightly as per #194 (comment).