Ignoring broken plugins

[isidentical]

Seems like there are a couple of broken plugins out there, and when any of them are installed in the system it completely blocks the usage of http/https commands. An example scenario;

$ pip install httpie
$ pip install httpie-aws-auth
$ http
Traceback (most recent call last):
  File "/usr/local/bin/http", line 8, in <module>
    sys.exit(main())
  File "/usr/local/lib/python3.9/site-packages/httpie/__main__.py", line 9, in main
    exit_status = main()
  File "/usr/local/lib/python3.9/site-packages/httpie/core.py", line 35, in main
    plugin_manager.load_installed_plugins()
  File "/usr/local/lib/python3.9/site-packages/httpie/plugins/manager.py", line 35, in load_installed_plugins
    plugin = entry_point.load()
  File "/usr/local/lib/python3.9/site-packages/pkg_resources/__init__.py", line 2450, in load
    return self.resolve()
  File "/usr/local/lib/python3.9/site-packages/pkg_resources/__init__.py", line 2456, in resolve
    module = __import__(self.module_name, fromlist=['__name__'], level=0)
  File "/usr/local/lib/python3.9/site-packages/httpie_aws_auth.py", line 8, in <module>
    from httpie import ExitStatus
ImportError: cannot import name 'ExitStatus' from 'httpie' (/usr/local/lib/python3.9/site-packages/httpie/__init__.py)

A straightforward solution for this is ignoring these errors, and throwing a warning to user (Warning: Failed to load 'httpie-aws-auth' plugin, see '/tmp/xxx.txt' for more logs). This way, even if the plugins fail they will continue to use the remaining possibilities of the httpie.

[PerfectlyInternal]

This seems pretty handy addition, and fairly simple to implement at that. I can start working on this now, if there aren't any other changes to be made. Are there any known broken plugins to test this with?

[isidentical]

, if there aren't any other changes to be made.

Unfortunately, there is. For not creating any conflicts, we need #1200 first (not directly relevant, but touches the same places this requires). After that, it should be very simple to do so.