[DES] parse by indent level

[Rekihyt]

Describe the change

Change parsing from a line by line approach to greedily accept lines as one App until indentation levels are the same.

Reason(s) for it to be added

Multi-line Apps, i.e. lists or patterns

[Rekihyt]

Don't use whitespace for parsing except in two cases:

• A single newline separates apps, unless they are operators or commas with empty second args
• A double newline separates everything.

Instead, indents will indicate parsing after the fact by the linter. If two lines are special cased into one expression, the linter will indent the second line.