Don't show the prompt to enable desktop notifications immediately after registration

[hughns]

I noticed that the DesktopNotificationsToast was showing up immediately after user registration even though it attempts to wait until 24 hours at

matrix-react-sdk/src/components/structures/MatrixChat.tsx

Lines 1409 to 1411 in 61076c3

	if (Notifier.shouldShowPrompt() && !MatrixClientPeg.userRegisteredWithinLastHours(24)) {
	showNotificationsToast(false);
	}

On investigating I found two issues:

1. mx_registration_time would never be present in LocalStorage at the time being checked. I believe this is because LocalStorage is being cleared during one of the calls to Lifecycle.doSetLoggedIn().
2. userRegisteredWithinLastHours() would always return false because the string value for mx_registration_time from LocalStorage was not being parsed properly (at least in Chrome): new Date("" + Date.now()) === Invalid Date

To address I have moved the tracking out of LocalStorage and doing it purely in memory (like how currentUserIsJustRegistered() is implemented).

I've also added some test cases to help maintain this in future.

---

Here's what your changelog entry will look like:

🐛 Bug Fixes

• Don't show the prompt to enable desktop notifications immediately after registration (#8274). Contributed by @hughns.

Preview: https://pr8274--matrix-react-sdk.netlify.app
⚠️ Do you trust the author of this PR? Maybe this build will steal your keys or give you malware. Exercise caution. Use test accounts.

[hughns]

For the record, this is what you currently see after registering a new user on app.element.io before you have done anything else:

[codecov]

Codecov Report

Merging #8274 (4f9d176) into develop (fe4683d) will increase coverage by 0.02%.
The diff coverage is 70.00%.

@@             Coverage Diff             @@
##           develop    #8274      +/-   ##
===========================================
+ Coverage    29.80%   29.83%   +0.02%     
===========================================
  Files          874      874              
  Lines        50017    50024       +7     
  Branches     12726    12728       +2     
===========================================
+ Hits         14908    14924      +16     
+ Misses       35109    35100       -9     

Impacted Files	Coverage Δ
src/Lifecycle.ts	1.42% <0.00%> (-0.02%)	⬇️
src/MatrixClientPeg.ts	30.33% <100.00%> (+17.39%)	⬆️

[t3chguy]

To address I have moved the tracking out of LocalStorage and doing it purely in memory (like how currentUserIsJustRegistered() is implemented).

This changes the intended behaviour, as now if the user refreshes at any point within 24 hours they'll be shown the prompt

currentUserIsJustRegistered - this method is very different in that it by definition only cares if the user has just right now in this session registered, this can be kept in memory.

userRegisteredWithinLastHours implies it has knowledge of outside of this session

[t3chguy]

See above

[hughns]

It looks I accidentally inverted some of the logic. I've reverted to localStorage based and taken steps to preserve the state during setLoggedIn()

[t3chguy]

Awesome, thanks!