Enable extending syntaxes to override indentation constraints

[deathaxe]

This commit introduces no_indent variable, inspired by Bash, to enable extending syntaxes to override indentation constraints.

Use cases:

• embed powershell in indented fenced code blocks in Markdown
• embed powershell in YAML files, such as Github Action workflows

Alternative:

A more general and easier to use approach would be to accept ST not tracking indentation and just allow to terminate HEREDOCs regardless leading whitespace in general. It would enable proper highlighting without further meassures being taken on 3rd-party syntaxes.

[michaelblyons]

A more general and easier to use approach would be to accept ST not tracking indentation and just allow to terminate HEREDOCs regardless leading whitespace in general. It would enable proper highlighting without further meassures being taken on 3rd-party syntaxes.

I know that would be easier. But people (like me!) are going to take their closing punctuation conventions from other languages...

for x in range(10):
    sql = """
        SELECT * FROM foo
    """

and be annoyed when this highlights like it is going to work, but find out that the string leaks:

    sql = @'
        SELECT * FROM foo
    '@