Add rustup to manifests (#1215)

* Add rustup to manifests

* Remove ManifestVersion

Manifest Schema Validation errors on key, as it is missing from type:
Microsoft.WinGetSvc.WinGet.Models.Manifest.Manifest

* Add missing tags from rustup Cargo.toml

* Remove extra installer

Schema validation fails as more than one installer is not yet supported

* Change publisher to Rust

manifests/Rust/rustup/1.21.1.yaml

@@ -0,0 +1,19 @@
+Id: Rust.rustup
+Publisher: Rust
+Name: rustup
+Version: 1.21.1
+AppMoniker: rustup
+Description: Manage multiple rust installations with ease
+Tags: rust, rustlang, rustup, multirust, install, proxy, toolchain
+Homepage: https://github.com/rust-lang/rustup
+MinOSVersion: 10.0.0.0
+License: MIT or Apache-2.0
+LicenseUrl: https://opensource.org/licenses/MIT or https://opensource.org/licenses/Apache-2.0
+Installers:
+  - Arch: x64
+    Url: https://static.rust-lang.org/rustup/archive/1.21.1/x86_64-pc-windows-gnu/rustup-init.exe
+    Sha256: D17DF34BA974B9B19CF5C75883A95475AA22DDC364591D75D174090D55711C72
+    InstallerType: exe
+    Switches:
+        Silent: "-y --quiet"
+        SilentWithProgress: "-y"