Resolve pr 846 comments

[bobhancockg]

Here's a summary of the key changes I made in AddDemandGenCampaign.java:

• I removed an API version comment.
• I updated the command line argument flags to use ArgumentNames constants.
• I modified the parameter parsing to allow hardcoding of your customer ID and video ID if you don't provide them via the command line.
• I initialized GoogleAdsClient to null.
• I removed unnecessary return statements after System.exit().
• I added a name to the Ad being created.
• I removed the business name and call to action text from Ad creation.
• I ensured the correct .build() call for AdGroupAdOperation.
• I made helper methods static for better encapsulation.

And here are the key changes in AddDemandGenCampaignTest.java:

• I updated it to use temporary ID constants from AddDemandGenCampaign.java.

Please note: I couldn't verify the tests due to a build environment incompatibility (Gradle version 7.6.4 and Java version 21). However, the code changes themselves are based on the review feedback.

Refactor: Ensure Demand Gen example constants are public and used by test

This commit addresses your feedback regarding the synchronization of temporary ID constants between AddDemandGenCampaign.java and its test file, AddDemandGenCampaignTest.java.

• Constants in AddDemandGenCampaign.java (BUDGET_TEMPORARY_ID, CAMPAIGN_TEMPORARY_ID, AD_GROUP_TEMPORARY_ID, LOGO_ASSET_TEMPORARY_ID, VIDEO_ASSET_TEMPORARY_ID) are now explicitly public static final long.
• AddDemandGenCampaignTest.java has been verified to use these public constants, with local definitions removed.

This ensures that the test file correctly references the authoritative constants from the main example class.

Note: I am still unable to run tests due to a build environment incompatibility (Gradle version 7.6.4 and Java version 21).