Enhance Select for robust object value support (#3893)

[jskupsik]

Fixes bugs preventing object (non-primitive) values from working correctly, and adds a generateOptionFn prop for resolving values not present in the current options list.

Bug fixes for object values

• doQueryAsync: dedupe via isEqual/unionWith instead of keyBy (string-key collision on objects).
• optionRenderer / selected-option matching: use deep equality so object values match and no longer render as [object Object] or collide with one another.

New generateOptionFn prop

• Synchronous (value) => SelectOption called when a selected value is not found among the current options (e.g. queryFn-based selects, readonly forms). Return null to fall back to the default value-as-label behavior.
• Resolves the label synchronously in findOption, so the value renders with its proper label on first paint - no async cache, reaction, or race conditions.

This supersedes the async lookupFn + _lookupCache approach earlier explored on this branch; the synchronous design is a much smaller, simpler footprint (just the prop plus the findOption fallback) and avoids the stale-cache / reaction-ordering bugs that approach was prone to.

Tested on desktop and mobile via the Toolbox companion PR (employee-by-id example renders the label, not the raw id, on mount, for a value not in the options list).

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• Caught up with develop branch as of last change.
• Added CHANGELOG entry, or determined not required.
• Reviewed for breaking changes, added breaking-change label + CHANGELOG if so.
• Updated doc comments / prop-types, or determined not required.
• Reviewed and tested on Mobile, or determined not required.
• Created Toolbox branch / PR, or determined not required.

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[jskupsik]

Testing lookupFn -

Before using lookupFn:

• Mobile:

• Desktop:

After using lookupFn:

• Mobile:

• Desktop

[jskupsik]

Toolbox PR: xh/toolbox#829

[lbwexler]

Could we make the lookupFunction synchronous? Is is more of a optionGenerator? This would simplify things greatly and assuage some concerns I am uncovering with timing and loops, and alot of the complexity.