SYSML2_ — Remove "Connection" from the names "FlowConnectionDefinition", "FlowConnectionUsage", and "SuccessionFlowConnectionUsage"

After resolution SYSML2_-403 to issue SYSML2_-173, FlowConnectionDefinition no longer specializes ConnectionDefinition (now specializing only ActionDefinition and KerML Interaction), and FlowConnectionUsage no longer specializes ConnectionUsage (now only specializing ActionUsage, ConnectorAsUsage and KerML ItemFlow. As a result of SYSML2_-403, having "Connection" in the name of the "Flow" classes causesconfusion among users that don't see the distinction between structure and behavior.

Renaming FlowConnectionDefinition to FlowDefinition and FlowConnectionUsage to FlowUsage would avoid confusion going forward. Not making this change prior to finalization of SysML v2 runs the risk of having confusion that would require complex deprecation steps to correct later.

Similarly for SuccessionFlowConnectionUsage, which specializes FlowConnectionUsage.

Rename "FlowConnectionDefinition", "FlowConnectionUsage", and "SuccessionFlowConnectionUsage" to remove "Connection"

This resolution consistently makes the following changes:

1. In the abstract syntax, changes FlowConnectionDefinition, FlowConnectionUsage and SuccessionFlowConnectionUsage to FlowDefinition, FlowUsage and SuccessionFlowUsage.
2. In the model library:
   • Changes FlowConnection and SuccessionFlowConnection to Flow and SuccessionFlow (and similarly for usages).
   • Changes MessageConnection to MessageAction and MessageTransferConnection to Message. (This avoids a conflict with the name MessageTransfer from the KerML Semantic Library Transfers model.)
   • Replaces the file FlowConnections.sysml with Flows.sysml.
3. In informal text, changes "message connection", "flow connection" and "succession flow connection" to "message", "flow" and "succession flow".

In addition, if resolution KERML_-131 to KERML_-107 (The term "Item" in KerML confusing against SysML) is approved by the KerML FTF, then there are additional changes to specialized elements from KerML. The resolution here also includes changes needed to accommodate resolution KERML_-131, conditional on its approval.