Support --format with xmllint

[bdovaz]

@nvuillam has not raised this issue so far?

It looks like you can at least configure the indent with the XMLLINT_INDENT environment variable:

https://gnome.pages.gitlab.gnome.org/libxml2/xmllint.html

[nvuillam]

• I didn't know it was possible ... but i didn't check, xmllint is inherited from super-linter who can not apply updates

Maybe we should allow it but disable it by default?

[bdovaz]

@nvuillam Questions:

1. How do I disable it by default? In the descriptor I have added cli_lint_fix_arg_name: "--format".
2. The environment variable XMLLINT_INDENT (string) is the one that controls the number of spaces:
   • How can I configure the linter so that this setting can be passed to it like any other linter configuration?
   • A class is needed for this, isn't it? Like a XmlLintLinter.py in order to redirect this configuration to this process

[nvuillam]

1. The current architecture does not allow to do that :D We have to think about it... maybe an additional variable XML_XMLLINT_AUTOFORMAT , that could be used in XmlLintLinter.py

2 descriptors allow to define custom variables :)
They will appear in the doc after build.sh --doc, but I'm not sure if it also updates JSON schema (in that case it must be done manually)

Example:

megalinter/megalinter/descriptors/spell.megalinter-descriptor.yml

Line 38 in c5561aa

variables: