tweak(gamemessage): Reduce number of MSG_DESTROY_SELECTED_GROUP messages

[Caball009]

• Similar to PRs tweak(gamemessage): Remove unused argument of MSG_DESTROY_SELECTED_GROUP #2664 and tweak(gamemessage): Remove unused MSG_AREA_SELECTION message from game logic #2667

The client considers primary mouse clicks in the game world as a deselection, and will also update the game logic. This means that GameMessage::MSG_DESTROY_SELECTED_GROUP messages are sent frequently, even if no objects are currently selected. There's actually an old EA comment on this issue. It's also unnecessary to send this message prior to the creation or selection of a new group.

This PR makes the following two changes:

1. a new check to verify that the local player has objects selected before creating a MSG_DESTROY_SELECTED_GROUP message.
2. Remove MSG_DESTROY_SELECTED_GROUP messages before other messages that already destroy group selection implicitly (MSG_CREATE_SELECTED_GROUP and GameMessage::MSG_SELECT_TEAM).

I've tested with two local clients in multiplayer (VS22 debug builds); one had this feature and one didn't, and everything worked fine.

See commits for cleaner diffs.

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Results for Golden Replay 1:

• MSG_NETWORK_MESSAGES: 56985
• MSG_LOGIC_CRC: 11601 (doesn't include 1785 for playback)
• MSG_DO_MOVETO: 6888
• MSG_AREA_SELECTION_DEPRECATED: 4476
• MSG_QUEUE_UNIT_CREATE: 2225
• MSG_DESTROY_SELECTED_GROUP: 17366
• MSG_CREATE_SELECTED_GROUP_NO_SOUND: 317, new group: 88
• MSG_CREATE_SELECTED_GROUP: 8299, new group: 8114
• MSG_DESTROY_SELECTED_GROUP before new group creation: 8901 (more than 8114 + 88, because this message is used twice sometimes).

Just the MSG_DESTROY_SELECTED_GROUP message before the creation of a new group accounts for 15% (8901 / 56985) of all network game messages in this replay. That doesn't even take into account how many times this message was used when no units were selected.

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TODO:

• Replicate in Generals.
• Do more thorough testing.

[greptile-apps]

Greptile Summary

This PR reduces redundant selection-group network messages. The main changes are:

• Emit destroy-selection messages only for non-empty selections.
• Remove destroy-selection messages superseded by group or team selection.
• Mirror the message-stream and UI changes in Generals and Zero Hour.

Confidence Score: 5/5

This looks safe to merge.

• No blocking issues found in the changed code.

Important Files Changed

Filename	Overview
Generals/Code/GameEngine/Source/Common/MessageStream.cpp	Filters destroy-selection messages that are immediately replaced by a new selection operation.
GeneralsMD/Code/GameEngine/Source/Common/MessageStream.cpp	Mirrors the Generals message filtering behavior for Zero Hour.
Generals/Code/GameEngine/Source/GameClient/InGameUI.cpp	Avoids emitting a destroy-selection message when no drawable was selected.
GeneralsMD/Code/GameEngine/Source/GameClient/InGameUI.cpp	Mirrors the conditional deselection message behavior for Zero Hour.
Core/GameEngine/Source/GameClient/MessageStream/SelectionXlat.cpp	Updates selection paths to use the revised deselection behavior.

_{Reviews (12): Last reviewed commit: "Replicated in Generals." | Re-trigger Greptile}

[xezon]

How confident are we that this will cause no gameplay issues?

[xezon]

Needs rebasing.

[Caball009]

Needs rebasing.

I just rebased. I held off on rebasing because I wanted to make it obvious to you (and myself) what the new changes were.

[Caball009]

Replicated in Generals.