VSCode extension should warn if there an error in Clarinet.toml

[hugocaillard]

Problem

If the manifest (clarinet.toml) is invalid, the VSCode extension will silently fail.
It can be reproduced with an invalid manifest like so

[contracts.contract]
path = 'contracts/traits/contract.clar'
clarity_version = 2
epoch = 2.4
clarity_version = 2
epoch = 2.4

Fix

Show an error popup in vscode