chore: Rename and standardize all GH workflows, and add an assistants_web check

[tianjing-li]

AI Description

This PR introduces a series of changes to the naming conventions and configurations of various GitHub workflow files. The modifications aim to standardise the naming structure and enhance clarity in the workflow definitions.

• Alembic-related workflows: The names of the workflows in alembic_duplicates.yml and alembic_migrations.yml have been updated to include the term "Alembic" for better context.
• Backend-related workflows: The names of the workflows in backend_integration_tests.yml, backend_lint.yml, backend_typecheck.yml, backend_unit_tests.yml, and docker_push_backend.yml have been modified to include the term "Backend" for improved clarity.
• Frontend-related workflows: The names of the workflows in docker_push_frontend.yml, frontend_coral_web_tests.yml, and frontend_slack_bot_tests.yml have been adjusted to include the term "Frontend" for better context.
• New workflow: A new workflow named frontend_assistants_web_tests.yml has been added, which is triggered on push events to the main branch and runs tests for the assistants_web interface.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 79.73%. Comparing base (083b530) to head (d3a271f).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #823   +/-   ##
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  Coverage   79.73%   79.73%           
=======================================
  Files         244      244           
  Lines       10486    10486           
=======================================
  Hits         8361     8361           
  Misses       2125     2125           

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[EugeneLightsOn]

looks good to me