Chore: update plugin id to avoid the "intellij" word usage

Signed-off-by: Daniel Hu <[email protected]>

src/main/resources/META-INF/plugin.xml

@@ -1,7 +1,7 @@
 <!-- Plugin Configuration File. Read more: https://plugins.jetbrains.com/docs/intellij/plugin-configuration-file.html -->
 <idea-plugin>
     <!-- Unique identifier of the plugin. It should be FQN. It cannot be changed between the plugin versions. -->
-    <id>ai.devchat.intellij</id>
+    <id>ai.devchat.plugin</id>
 
     <!-- Public plugin name should be written in Title Case.
          Guidelines: https://plugins.jetbrains.com/docs/marketplace/plugin-overview-page.html#plugin-name -->