rename ignoreClasses to discardClasses

[richardelms]

rename ignoreClasses to discardClasses

Refactoring: Terminology Change from "Ignore" to "Discard"

• Renamed all references of ignoreClasses to discardClasses in the main configuration (Configuration.java), the Bugsnag client (Bugsnag.java), and the appender (BugsnagAppender.java). This includes method names, variable names, and internal logic. [1] [2] [3]
• Updated the logic that determines whether an exception class should be reported, now checking discardClasses instead of ignoreClasses.
• Updated all related logging messages and documentation comments to use "discard" terminology. [1] [2]

Backward Compatibility

• Added deprecated methods (setIgnoredClass) in BugsnagAppender.java that delegate to the new setDiscardClass methods, ensuring existing integrations do not break.

[lemnik]

LGTM