feat: Add support for apiEndpoint and deprecate serviceAddress client configuration option.

[yoshi-automation]

This PR was generated using Autosynth. 🌈

Here's the log from Synthtool:

synthtool > Executing /tmpfs/src/git/autosynth/working_repo/Tasks/synth.py.
synthtool > Ensuring dependencies.
synthtool > Pulling artman image.
0.29.1: Pulling from googleapis/artman
Digest: sha256:b2a73f4dda03ef8fcaa973e3ba26d0cf34091f6c22c70add663af325931aef4d
Status: Image is up to date for googleapis/artman:0.29.1
synthtool > Cloning googleapis.
synthtool > Running generator for google/cloud/tasks/artman_cloudtasks_v2.yaml.
synthtool > Generated code into /home/kbuilder/.cache/synthtool/googleapis/artman-genfiles/php/google-cloud-tasks-v2.
synthtool > Running generator for google/cloud/tasks/artman_cloudtasks_v2beta2.yaml.
synthtool > Generated code into /home/kbuilder/.cache/synthtool/googleapis/artman-genfiles/php/google-cloud-tasks-v2beta2.
synthtool > Running generator for google/cloud/tasks/artman_cloudtasks_v2beta3.yaml.
synthtool > Generated code into /home/kbuilder/.cache/synthtool/googleapis/artman-genfiles/php/google-cloud-tasks-v2beta3.
synthtool > Replaced "'serviceAddress' =>" in src/V2beta3/Gapic/CloudTasksGapicClient.php.
synthtool > Replaced "'serviceAddress' =>" in src/V2beta2/Gapic/CloudTasksGapicClient.php.
synthtool > Replaced "'serviceAddress' =>" in src/V2/Gapic/CloudTasksGapicClient.php.
synthtool > Replaced '@type string \\$serviceAddress' in src/V2beta3/Gapic/CloudTasksGapicClient.php.
synthtool > Replaced '@type string \\$serviceAddress' in src/V2beta2/Gapic/CloudTasksGapicClient.php.
synthtool > Replaced '@type string \\$serviceAddress' in src/V2/Gapic/CloudTasksGapicClient.php.
synthtool > Replaced '\\$transportConfig, and any \\$serviceAddress' in src/V2beta3/Gapic/CloudTasksGapicClient.php.
synthtool > Replaced '\\$transportConfig, and any \\$serviceAddress' in src/V2beta2/Gapic/CloudTasksGapicClient.php.
synthtool > Replaced '\\$transportConfig, and any \\$serviceAddress' in src/V2/Gapic/CloudTasksGapicClient.php.
synthtool > Replaced 'Copyright \\d{4}' in src/V2beta3/CloudTasksClient.php.
synthtool > Replaced 'Copyright \\d{4}' in src/V2beta3/CloudTasksGrpcClient.php.
synthtool > Replaced 'Copyright \\d{4}' in src/V2beta3/Gapic/CloudTasksGapicClient.php.
synthtool > Replaced 'Copyright \\d{4}' in src/V2beta2/CloudTasksClient.php.
synthtool > Replaced 'Copyright \\d{4}' in src/V2beta2/CloudTasksGrpcClient.php.
synthtool > Replaced 'Copyright \\d{4}' in src/V2beta2/Gapic/CloudTasksGapicClient.php.
synthtool > Replaced 'Copyright \\d{4}' in tests/Unit/V2beta3/CloudTasksClientTest.php.
synthtool > Replaced 'Copyright \\d{4}' in tests/Unit/V2beta2/CloudTasksClientTest.php.
synthtool > Replaced 'Copyright \\d{4}' in tests/System/V2beta3/TasksServiceSmokeTest.php.
synthtool > Replaced 'Copyright \\d{4}' in tests/System/V2beta2/TasksServiceSmokeTest.php.
synthtool > Replaced 'Copyright \\d{4}' in src/V2/CloudTasksClient.php.
synthtool > Replaced 'Copyright \\d{4}' in src/V2/CloudTasksGrpcClient.php.
synthtool > Replaced 'Copyright \\d{4}' in src/V2/Gapic/CloudTasksGapicClient.php.
synthtool > Replaced 'Copyright \\d{4}' in tests/Unit/V2/CloudTasksClientTest.php.
synthtool > Replaced 'Copyright \\d{4}' in tests/System/V2/TasksServiceSmokeTest.php.
synthtool > No replacements made in src/*/Gapic/CloudTasksGapicClient.php for pattern Task_View, maybe replacement is not longer needed?
synthtool > Replaced 'will be removed in the next major release' in src/V2beta3/Task_View.php.
synthtool > Replaced 'will be removed in the next major release' in src/V2beta3/Queue_State.php.
synthtool > Replaced 'will be removed in the next major release' in src/V2beta2/Task_View.php.
synthtool > Replaced 'will be removed in the next major release' in src/V2beta2/Queue_State.php.
synthtool > Replaced 'will be removed in the next major release' in src/V2/Task_View.php.
synthtool > Replaced 'will be removed in the next major release' in src/V2/Queue_State.php.
synthtool > Replaced '^(\\s+\\*\\n)?\\s+\\*\\s@experimental\\n' in src/V2/CloudTasksClient.php.
synthtool > Replaced '^(\\s+\\*\\n)?\\s+\\*\\s@experimental\\n' in src/V2/Gapic/CloudTasksGapicClient.php.
synthtool > Cleaned up 0 temporary directories.
synthtool > Wrote metadata to synth.metadata.