Fix ExtremeXOS sysDescr date parsing

[benniej]

Description

Updates the ExtremeXOS sysDescr parsing to handle other date formats.

Some ExtremeXOS devices return the build date in different layouts, including different positions for the day, year, time, AM/PM and timezone.

Changes

• Added support for additional ExtremeXOS date layouts.
• Added error handling around date and timezone parsing.
• Trim whitespace from sysDescr before parsing.
• Added test cases for the additional ExtremeXOS sysDescr formats.

Testing

Ran the platform tests:

[benniej@devbox0 OSS_SNMP]$ ./vendor/bin/phpunit tests/Tests/OSS_SNMP/Platforms/
PHPUnit 9.6.3 by Sebastian Bergmann and contributors.

.........................................                         41 / 41 (100%)

Time: 00:00.054, Memory: 6.00 MB

OK (41 tests, 205 assertions)