Fix 'variable declared but its value is never read' Typescript errors

[fketchakeu]

This PR allows for using live-plugin-manager in a typescript project with noUsedParameters and/or noUnusedLocals set to true. Otherwise we get the following errors at build time:

node_modules/live-plugin-manager/src/fileSystem.ts:60:37 - error TS6133: 'filterDest' is declared but its value is never read.

60  const filter = (filterSrc: string, filterDest: string) => {
                                       ~~~~~~~~~~

node_modules/live-plugin-manager/src/PluginManager.ts:584:51 - error TS6133: 'version' is declared but its value is never read.

584  private async getDownloadedPackage(name: string, version: string): Promise<PackageInfo | undefined> {
                                                      ~~~~~~~

node_modules/live-plugin-manager/src/PluginVm.ts:185:13 - error TS6133: 'request' is declared but its value is never read.

185             paths: (request: string) => null // TODO I should I populate this

[davideicardi]

Thanks!