Change install string text to reflect plugin instead of extension (#4481)

Author: manodnyab

plugins/toolkit/resources/resources/software/aws/toolkits/resources/MessagesBundle.properties

@@ -797,7 +797,7 @@ codewhisperer.explorer.enable=Start
 codewhisperer.explorer.enabled=\   Enabled
 codewhisperer.explorer.learn=Learn
 codewhisperer.explorer.node.dismiss=Dismiss
-codewhisperer.explorer.node.install_q=Install the Amazon Q Extension
+codewhisperer.explorer.node.install_q=Install the Amazon Q Plugin
 codewhisperer.explorer.pause_auto=Pause Auto-Suggestions
 codewhisperer.explorer.pause_auto_scans =Pause Auto-Scans
 codewhisperer.explorer.paused=\   Paused