refactor: Restructure linters

This is our first major refactoring. Several concepts didn't play out
the way we initially thought, and that's ok.

Highlights are:
* Reporters shall no longer produce actual "reports" but rather
  create "LintMessages" and "CoverageInfo"
* Linters become more independent but share a common signature
  ("LinterParameters")
* Linters access and share resources via a @ui5/fs
  "workspace" instance. Resource paths reflect UI5 runtime paths
* Linters are generally async and executed concurrently
  (eventually in workers if we can proof performance improvements)
* A LinterContext instance is proveded to all linters.
    * Linters provide it with their produced  "LintMessages" and
      "CoverageInfo" from which the final "LintResult" is generated.
* The "ui5Types"-Linter is special and executed after all other linters
  have finished (to take any transpiled resources into account)

src/cli/base.ts

@@ -12,7 +12,7 @@ import ConsoleWriter from "@ui5/logger/writers/Console";
 
 export interface LinterArg {
 	coverage: boolean;
-	filePaths: string[];
+	filePaths?: string[];
 	details: boolean;
 	format: string;
 }