[AIRFLOW-XXX] Example for BigQuery to BigQuery operator

[sann3]

Example for BigQuery to BigQuery operator.

Accommodated all the changes mentioned here

[codecov-io]

Codecov Report

Merging #6259 into master will increase coverage by 0.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #6259      +/-   ##
==========================================
+ Coverage   80.05%   80.07%   +0.01%     
==========================================
  Files         610      611       +1     
  Lines       35264    35270       +6     
==========================================
+ Hits        28232    28241       +9     
+ Misses       7032     7029       -3

Impacted Files	Coverage Δ
...rflow/example_dags/example_bigquery_to_bigquery.py	100% <100%> (ø)
airflow/utils/dag_processing.py	56.55% <0%> (-0.35%)	⬇️
airflow/bin/cli.py	66.38% <0%> (+0.2%)	⬆️
airflow/operators/bigquery_to_bigquery.py	100% <0%> (+6.45%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 76fe45e...f23de31. Read the comment docs.

[sann3]

Is anything pending from my side?

[mik-laj]

Personally, I would prefer all examples for GCP to have system tests
#6227 (comment)

After that, an example for this operator is already in the repository.
https://github.com/apache/airflow/blob/master/airflow/gcp/example_dags/example_bigquery.py#L159-L163
This example has system tests.

[mik-laj]

This change must also have a ticket
#6227 (comment)

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.