Update last update check time when choosing to install update

[zorgiepoo]

In the UI driver, this is when the user chooses to Install & Relaunch.

In the automatic download based driver, this is when Sparkle hands off responsibility to its delegate to install the update and they trigger the callback to relaunch the app.

This defers checking for updates on next relaunch too quick when an update was just installed. This matters if there is a long delay between the user being presented an update and them actually installing it, for example.

Fixes #2135

Misc Checklist:

• My change requires a documentation update on Sparkle's website repository
• My change requires changes to generate_appcast, generate_keys, or sign_update

Only bug fixes to regressions or security fixes are being backported to the 1.x (master) branch now. If you believe your change is significant enough to backport, please also create a separate pull request against the master branch.

Testing

I tested and verified my change by using one or multiple of these methods:

• Sparkle Test App
• Unit Tests
• My own app
• Other (please specify)

Tested that test app updated and last check update time in user defaults got updated.
Probe update check works from sparkle-cli (when new update is available and isn't available).
Tested that automatic update driver updates last check date when delegate calls block to install/relaunch app, using Test App.

macOS version tested: 12.4 (21F79)