New sub-command: `compile view` for off-chain view compilation

Motivation and Context

Description

Component

• compiler
• website
• webide
• vscode-plugin
• debugger

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Performance improvement (non-breaking change that improves performance)
• None (change with no changelog)

Changelog

The new sub-command compile view allows to compile views directly. This can be useful for compiling off-chain views to be used in metadata:

$ cat off_view.mligo 
let main (p : int) (s : int) : operation list * int = [], p + s

let v (p : string) (s : int) : int = String.length p + s
$ ligo compile view off_view.mligo v --michelson-format json
{"parameter":{"prim":"string"},"returnType":{"prim":"int"},"code":[{"prim":"UNPAIR"},{"prim":"SIZE"},{"prim":"ADD"}]}

Checklist:

• If a new syntax has been introduced, put a message on slack ligo-lsp
• Changes follow the existing coding style (use dune @fmt to check).
• Tests for the changes have been added (for bug fixes / feature).
• Documentation has been updated.
• Changelog description has been added (if appropriate).
• Start titles under ## Changelog section with #### (if appropriate).
• There is no image or uploaded file in changelog
• Examples in changed behaviour have been added to the changelog (for breaking change / feature).