feat: Add dataplane code snippets for feature store service

[lclc19]

This is a follow up PR for dataplane code snippets for feature store service

[snippet-bot]

Here is the summary of changes.

You are about to add 4 region tags.

• samples/snippets/feature_store_service/batch_create_features_sample.py:19, tag aiplatform_batch_create_features_sample
• samples/snippets/feature_store_service/batch_read_feature_values_sample.py:20, tag aiplatform_batch_read_feature_values_sample
• samples/snippets/feature_store_service/import_feature_values_sample.py:19, tag aiplatform_import_feature_values_sample
• samples/snippets/feature_store_service/read_feature_values_sample.py:19, tag aiplatform_read_feature_values_sample

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[lclc19]

Re guidance for parameters list:
Same as #713 (comment), we need to expose the request construction explicitly in order for the sample to be educational. We expect the usage for this snippet is that a user fill in all the parameters as seen in the function signature, then the snippet should work as expected, and the user can later tweak the hard coded part to fulfill their specialized use.

[nicain]

• Import dependencies
• Instantiate the client library
• Handle authentication
• Prepare an API request
• Exercise the API
• Process the result
• Use correct region tags
• Region tags updated in cloud.google.com
• Self-contained, copy-paste-runnable
• Descriptive top-level comment
• Code comments in the body of the code snippet
• Lines of code (and 120 char lines)
• Levels of indirection
• Cyclomatic complexity
• Variable instantiation
• Variable types
• Adhere to language idioms
• Handle errors
• Test coverage
• Portable in multiple environments

[nicain]

Updates make this LGTM.

You may want to verify that your region tags are consistent with those in the documentation, I haven't checked those but don't want to block you.

[lclc19]

Updates make this LGTM.

You may want to verify that your region tags are consistent with those in the documentation, I haven't checked those but don't want to block you.

Thanks, double checked the region tags to make sure they are conforming to go/code-snippets-style#use-correct-region-tags