deps: use normalizePath from @rollup/pluginutils (ezolenko#320)

- this was introduced in v4.1.0 of @rollup/pluginutils:
  https://github.com/rollup/plugins/blob/master/packages/pluginutils/CHANGELOG.md#v410

- this is the same as the code in `normalize.ts` but it uses constants
  from Node and is used by multiple Rollup plugins, so just helps with
  standardization
  - also less code and types to ship in the bundle!

- removed the dist files for `normalize` as well, but didn't do a build
  in this commit as those are usually done in separate commits

Author: agilgur5

dist/normalize.d.ts

@@ -1,7 +1,7 @@
 import { tsModule } from "./tsproxy";
 import * as tsTypes from "typescript";
 import * as _ from "lodash";
-import { normalize } from "./normalize";
+import { normalizePath as normalize } from "@rollup/pluginutils";
 import { TransformerFactoryCreator } from "./ioptions";
 
 export class LanguageServiceHost implements tsTypes.LanguageServiceHost

dist/normalize.d.ts.map

@@ -13,7 +13,7 @@ import { printDiagnostics } from "./print-diagnostics";
 import { TSLIB, TSLIB_VIRTUAL, tslibSource, tslibVersion } from "./tslib";
 import { blue, red, yellow, green } from "colors/safe";
 import { relative, dirname, normalize as pathNormalize, resolve as pathResolve } from "path";
-import { normalize } from "./normalize";
+import { normalizePath as normalize } from "@rollup/pluginutils";
 import findCacheDir from "find-cache-dir";
 
 import { PluginImpl, PluginContext, InputOptions, OutputOptions, TransformResult, SourceMap, Plugin } from "rollup";