[#5820] Outgoing Activity Locale being Overwritten

[ceciliaavila]

Fixes #5820

Description

This PR updates the Activity's ApplyConversationReference method to prioritize the activity's locale over the reference locale.

Specific Changes

• Updated ApplyConversationReference method in ActivityEx class to use the activity's locale first. If it's null, use the reference's locale.
• Updated unit tests to assert the right locale values.

Testing

These images show the overridden locale property (before) and how it's kept after the changes.

BEFORE:

AFTER:

[coveralls]

Pull Request Test Coverage Report for Build 350384

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 79.093%

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Totals
Change from base Build 349053:	0.0%
Covered Lines:	25827
Relevant Lines:	32654

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💛 - Coveralls

[BruceHaley]

✔️ No Binary Compatibility issues for Microsoft.Bot.Schema.dll