feat: trailing commas

[novusnota]

• struct instantiations
• initOf arguments
• init() parameters
• inherited traits via with
• function arguments and parameters

Closes #164

[novusnota]

Oh, okay, that's reasonable. I'll try to leave explicit mentions of them on contract, functions and expressions pages and remove implicit usage elsewhere. Thinking of leaving them be for with lists though, but maybe not.

UPD: Came up with a consistent formatting approach — just match Dart's style, which is, implicitly, your recommendation as well. Trailing commas imply separate line formatting, while not having them keeps stuff on the same line.

[anton-trunov]

@novusnota I updated the list of checks for the linter issue: https://github.com/tact-lang/tact/issues/295

[novusnota]

Awesome!