Log the reason a config entry failed to setup

[bdraco]

Proposed change

Log the reason a config entry failed to setup

If we pass a string to ConfigEntryNotReady or raise it from
another exception we now log the string passed or the
string generated by the original exception.

With #47201 this makes it easy for developers to still show
the reason why setup failed without having to worry about log
spam from additional attempts by rasing ConfigEntryNotReady
from the original exception.

Example with heos below:

2021-03-28 22:00:15 WARNING (MainThread) [homeassistant.config_entries] Config entry 'Controller (192.168.107.76)' for heos integration not ready yet: [Errno 111] Connect call failed ('192.168.107.76', 1255); Retrying in background
2021-03-28 22:00:17 WARNING (MainThread) [homeassistant.config_entries] Config entry 'maui hp 89' for ipp integration not ready yet; Retrying in background
2021-03-28 22:00:22 DEBUG (MainThread) [homeassistant.config_entries] Config entry 'Controller (192.168.107.76)' for heos integration not ready yet: [Errno 111] Connect call failed ('192.168.107.76', 1255); Retrying in 10 seconds
2021-03-28 22:00:25 DEBUG (MainThread) [homeassistant.config_entries] Config entry 'maui hp 89' for ipp integration not ready yet; Retrying in 10 seconds
2021-03-28 22:00:25 WARNING (MainThread) [homeassistant.config_entries] Config entry 'Marantz NR1711' for denonavr integration not ready yet; Retrying in background
2021-03-28 22:00:32 DEBUG (MainThread) [homeassistant.config_entries] Config entry 'Controller (192.168.107.76)' for heos integration not ready yet: [Errno 111] Connect call failed ('192.168.107.76', 1255); Retrying in 20 seconds
2021-03-28 22:00:38 DEBUG (MainThread) [homeassistant.config_entries] Config entry 'maui hp 89' for ipp integration not ready yet; Retrying in 20 seconds
2021-03-28 22:00:40 DEBUG (MainThread) [homeassistant.config_entries] Config entry 'Marantz NR1711' for denonavr integration not ready yet; Retrying in 10 seconds
2021-03-28 22:00:52 DEBUG (MainThread) [homeassistant.config_entries] Config entry 'Controller (192.168.107.76)' for heos integration not ready yet: [Errno 111] Connect call failed ('192.168.107.76', 1255); Retrying in 40 seconds
2021-03-28 22:01:00 DEBUG (MainThread) [homeassistant.config_entries] Config entry 'Marantz NR1711' for denonavr integration not ready yet; Retrying in 20 seconds
2021-03-28 22:01:01 DEBUG (MainThread) [homeassistant.config_entries] Config entry 'maui hp 89' for ipp integration not ready yet; Retrying in 40 seconds

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New integration (thank you!)
• New feature (which adds functionality to an existing integration)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Example entry for configuration.yaml:

# Example configuration.yaml

Additional information

• This PR fixes or closes issue: fixes #
• This PR is related to issue:
• Link to documentation pull request:

Checklist

• The code change is tested and works locally.
• Local tests pass. Your PR cannot be merged unless tests pass
• There is no commented out code in this PR.
• I have followed the development checklist
• The code has been formatted using Black (black --fast homeassistant tests)
• Tests have been added to verify that the new code works.

If user exposed functionality or configuration variables are added/changed:

• Documentation added/updated for www.home-assistant.io

If the code communicates with devices, web services, or third-party tools:

• The manifest file has all fields filled out correctly.
  Updated and included derived files by running: python3 -m script.hassfest.
• New or updated dependencies have been added to requirements_all.txt.
  Updated by running python3 -m script.gen_requirements_all.
• Untested files have been added to .coveragerc.

The integration reached or maintains the following Integration Quality Scale:

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To help with the load of incoming pull requests:

• I have reviewed two other open pull requests in this repository.

[MartinHjelmare]

Looks good!