Cherry pick PR #8935: Implement time zone monitor for linux

[cobalt-github-releaser-bot]

Refer to the original PR: #8935

Adds a time zone monitor for Linux platforms using inotify. It observes
changes to system time zone configuration files such as /etc/localtime.
Upon detecting a modification, a kSbEventDateTimeConfigurationChanged
event is injected into the Starboard application event queue. This allows
Cobalt to dynamically react to system time zone updates without requiring
a restart, improving time-sensitive feature consistency.

Have to remove the time zone caching mechanism in starboard/shared/linux/time_zone_get_name.cc to redetermine time zone from system whenever SbTimeZoneGetName is called. Check the SbTimeZoneGetName implementation on ATV, ATV does not have the caching mechanism to determine the time zone only once either.

The TimeZoneMonitor class uses a inifinite blocking poll command to watch system time zone files, and non-blocking read command to read the time zone change to buffer to avoid read command hanging the thread, and a blocking write command to signal the destruction of TimeZoneMonitor.

Test: (on evergreen-x64)
Before this change: http://screencast/cast/NDc5OTQwMDc5MzYwNDA5Nnw1MjJlOWM1OC00Yg
After this change: http://screencast/cast/NTg2NDY3NDA0OTM5MjY0MHw4NmIwOThjZS0zMw
Bug: 448161236

[github-actions]

🤖 Gemini Suggested Commit Message

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linux: Implement time zone monitor for Linux

This change introduces a TimeZoneMonitor class for Linux platforms. It uses
inotify to observe changes to system time zone configuration files like
/etc/localtime. When a modification is detected, a
kSbEventDateTimeConfigurationChanged event is injected into the Starboard
application event queue.

This enables Cobalt to dynamically react to system time zone updates
without requiring an application restart, thereby improving consistency
for time-sensitive features. Additionally, the time zone caching
mechanism in SbTimeZoneGetName has been removed to ensure the system's
current time zone is always re-determined upon query.

Bug: 448161236

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[gemini-code-assist]

Code Review

This pull request cherry-picks the implementation of a time zone monitor for Linux. The changes correctly introduce the TimeZoneMonitor to watch for system time zone file modifications and inject an event upon detection. The removal of the time zone caching in SbTimeZoneGetName is also correctly implemented to allow for dynamic updates.

While reviewing the implementation, I found an opportunity to improve the robustness of the TimeZoneMonitor by handling inotify queue overflows. This is an edge case, but handling it would make the monitor more resilient. Please see the specific comment for details.