intellij project files update

Current versions of Intellij are failing to parse the current vcs.xml file as it has a comment before the optional xml declaration.

![image](https://user-images.githubusercontent.com/217262/148092170-f45c06bc-d79a-40d4-878e-04d146d04648.png)

I've updated that to not complain as well as added another entry for the .gitignore for a common intellij plugin. This should make it easier for contributors to open the project. Currently on a fresh clone you get a dirty vcs.xml file.

Fixes #2799

COPYBARA_INTEGRATE_REVIEW=#2799 from codylerum:intellij_excludes 2793f0c
PiperOrigin-RevId: 424084925

.gitignore

@@ -8,6 +8,7 @@
 
 # intellij
 .idea/ant.xml
+.idea/codestream.xml
 .idea/codeStyleSettings.xml
 .idea/compiler.xml
 .idea/copyright