[next] decouple next from azure-cli-core and support personalized recommendation

[zhoxing-ms]

Associated core PR: Azure/azure-cli#17009

Description for decoupling part:

• The logic of log_command_history() is invoked in load_command_table() to log the command history for az next.
  ALWAYS_LOADED_EXTENSIONS = ['azext_next'] is declared in azure-cli-core to ensure that this logic will be called after next extension is installed.

• Modify the environment variable AZURE_CORE_USE_COMMAND_INDEX=False, and then reload the command table in log_command_history() to skip command index
  But cli_ctx.invocation.commands_loader.load_command_table(args) will not only reload a new object of NextCommandsLoader, but also recursively calls load_command_table() again, and fall into infinite nested call. So NextCommandsLoader is designed as a singleton, and _has_reload_command_table is used to avoid infinite nested calls.

• Delete method log_latest_error_info(), clean_exception_history() and get exception information from Telemetry cache

---

This checklist is used to make sure that common guidelines for a pull request are followed.

General Guidelines

• Have you run azdev style <YOUR_EXT> locally? (pip install azdev required)
• Have you run python scripts/ci/test_index.py -q locally?

For new extensions:

• My extension description/summary conforms to the Extension Summary Guidelines.

About Extension Publish

There is a pipeline to automatically build, upload and publish extension wheels.
Once your PR is merged into master branch, a new PR will be created to update src/index.json automatically.
The precondition is to put your code inside this repo and upgrade the version in the PR but do not modify src/index.json.

[yonzhan]

next

[jsntcy]