Make Integrations team codeown source integrations (#4561)

We have a dedicated team for our source integrations. This commit modifies CODEOWNERS so that they own those integrations.

It does not fiddle with proto/ codeownership, because that's going to be a mess to untangle and isn't related to the actual review requests that motivated this change. It also doesn't make the Integrations team codeown our more experimental/unusual sources:

- GitHub Experimental
- Huggingface
- stdin
- syslog

Author: rosecodym

CODEOWNERS

@@ -2,8 +2,23 @@
 * @trufflesecurity/product-eng
 
 # Scanning
+pkg/sources/ @trufflesecurity/Scanning
 pkg/writers/ @trufflesecurity/Scanning
 
+# Integrations
+pkg/sources/circleci/ @trufflesecurity/Integrations
+pkg/sources/docker/ @trufflesecurity/Integrations
+pkg/sources/elasticsearch/ @trufflesecurity/Integrations
+pkg/sources/filesystem/ @trufflesecurity/Integrations
+pkg/sources/gcs/ @trufflesecurity/Integrations
+pkg/sources/git/ @trufflesecurity/Integrations
+pkg/sources/github/ @trufflesecurity/Integrations
+pkg/sources/gitlab/ @trufflesecurity/Integrations
+pkg/sources/jenkins/ @trufflesecurity/Integrations
+pkg/sources/postman/ @trufflesecurity/Integrations
+pkg/sources/s3/ @trufflesecurity/Integrations
+pkg/sources/travisci/ @trufflesecurity/Integrations
+
 # Shared
 pkg/decoders/ @trufflesecurity/Scanning @trufflesecurity/OSS
 pkg/engine/ @trufflesecurity/Scanning  @trufflesecurity/OSS
@@ -12,7 +27,6 @@ pkg/giturl/ @trufflesecurity/Scanning  @trufflesecurity/OSS
 pkg/handlers/ @trufflesecurity/Scanning  @trufflesecurity/OSS
 pkg/iobuf/ @trufflesecurity/Scanning  @trufflesecurity/OSS
 pkg/sanitizer/ @trufflesecurity/Scanning  @trufflesecurity/OSS
-pkg/sources/ @trufflesecurity/Scanning  @trufflesecurity/OSS
 proto/ @trufflesecurity/Scanning  @trufflesecurity/OSS
 
 # OSS