• prevent running ansible-lint if incompatible yamllint custom settings are found
• report incompatible yamllint settings
• update documentation to explain which options are divergent and why

This change has the potential of breaking linting for users that do have a custom .yamllint config file. Still, the error given should make the fix very easy as it will mention each option that needs to be changed and to which value, like below:

CRITICAL Found incompatible custom yamllint configuration (.yamllint), please either remove the file or edit it to comply with:

• comments.min-spaces-from-content must be 1
• braces.min-spaces-inside must be 0
• braces.max-spaces-inside must be 1
• octal-values.forbid-implicit-octal must be true
• octal-values.forbid-explicit-octal must be true

Read https://ansible.readthedocs.io/projects/lint/rules/yaml/ for more details regarding why we have these requirements.

This change ensures that when running --fix we do not end-up with a regression regarding number of yamllint rule violations. As mentioned inside the documentation, there are technical and compatibility reasons why we cannot make these few options configurable.

Fixes: #3890
Fixes: #4118