updater: Add log window and additional log messages

[notr1ch]

Description

Adds a log window (hidden by default) and a "Show Log" button to the updater, and makes the updater more verbose by logging more of its actions to the log window to aid in debugging.

Disclaimer: Initial implementation was aided by LLM generated code, most of which was rewritten.

Motivation and Context

Hopefully find the cause of spurious update failures for some users.

How Has This Been Tested?

Upgrading and downgrading from RC / Stable.

Types of changes

• New feature (non-breaking change which adds functionality)

Checklist:

• My code has been run through clang-format.
• I have read the contributing document.
• My code is not on the master branch.
• The code has been tested.
• All commit messages are properly formatted and commits squashed where appropriate.
• I have included updates to all appropriate documentation.

[RytoEX]

Tentatively seems fine, and I'd like to ship the updater updates before next release.

[notr1ch]

Updated to remove raw pointers in Log / PostMessage / WM_LOG_MESSAGE handling.