Consolidate update+reader & remove some dead code

Sources/dpk-cli/Subcommands/DpkSearchCommand.swift

@@ -44,7 +44,7 @@ struct DpkSearchCommand: AsyncParsableCommand {
     let localRepositories = try await ApkRepositoriesConfig()
     let index: ApkIndex
     do {
-      index = try await ApkIndex.resolve(localRepositories, fetch: .local)
+      index = try await ApkIndexReader.resolve(localRepositories, fetch: .local)
     } catch {
       eprint("Failed to build package index: \(error.localizedDescription)")
       throw .failure

Sources/dpk-cli/Subcommands/DpkUpdateCommand.swift

@@ -19,7 +19,7 @@ struct DpkUpdateCommand: AsyncParsableCommand {
   func run() async throws {
     let repositories = try await ApkRepositoriesConfig().repositories
     eprint("Updating package repositories")
-    let index = try await ApkIndex.resolve(repositories, fetch: self.lazyDownload ? .lazy : .update)
+    let index = try await ApkIndexReader.resolve(repositories, fetch: self.lazyDownload ? .lazy : .update)
     eprint("Indexed \(index.packages.count) package(s)")
   }
 }