fix(lsp): ast-from-position fixes

[idoros]

This PR fix a couple of errors in ast-from-position that is used to identified source context for the language-service:

• fix: @name |params should resolve where to atRuleParams and not atRuleBody
• fix: resolve at-rule params the entire prelude including afterName, params, between (params and ; or {), and potential space for last unclosed at-rule
• fix: resolve declaration value from including anything from colon, actual value, and potential space for last unclosed declaration
• chore : improve deindent config in test-kit