Add guidance to linter

[tdegeus]

For math environments there are no options and arguments. This could hold for custom commands environments as well. A way to guide the implementation could be to provide

Command-line guidance:

--args="{tabular}[1]{3}"  # environment with one option and three arguments
--args="\TG"  # command without any options or arguments
--args="\foo{2}"  # command with two arguments (and no options)

Or instead or in addition

--newcommand={\foo}[3][...]{...}  # command with one option and two arguments -- LaTeX syntax
--newenvironment{env}[3][...]{...}{...}  # environment with one option and two arguments -- LaTeX syntax

see below

In addition those commands present in the preamble could be read. And the user could add

% \texindent\newcommand{\foo}[3][...]{...}
% \texindent\newenvironment{env}[3][...]{...}{...}

for a command respectively an environment with one option and two arguments.
Note that ... is ignored.

[tdegeus]

Implementation:

class TexEnvironment:

    def __init__(self, name: str, nopts: int = None, nargs: int = None):
        self.name = name
        self.nopts = nopts
        self.nargs = nnargs

    def text_to_placeholders(...)