add name and remove language from LanguageTag

[samuelstroschein]

Problem

The LanguageTag AST contains language property which is supposed to be an ISO-639 identifier but that is not validated. Enforcing ISO-639 ids prevents projects to adopt inlang when they already use country code mixes like en-US.

Proposal

Remove the language property and add name.

name can be an arbitrary identifier and will be deprecated when language tags are fully supported. That opens the possibility to support language-country identifiers now without implementing constant string-based conditional logic.