message: Update Mono and OmniSharp depedencies
diff: "runtimeDependencies": [
  {
  "description": "Mono Runtime (Linux / x86)",
  - "url": "https://omnisharpdownload.blob.core.windows.net/ext/mono.linux-x86-4.6.1.zip",
  + "url": "https://omnisharpdownload.blob.core.windows.net/ext/mono.linux-x86-4.8.0.478.zip",
  "installPath": "./bin",
  "platforms": [
  "linux"
  },
  {
  "description": "Mono Runtime (Linux / x64)",
  - "url": "https://omnisharpdownload.blob.core.windows.net/ext/mono.linux-x86_64-4.6.1.zip",
  + "url": "https://omnisharpdownload.blob.core.windows.net/ext/mono.linux-x86_64-4.8.0.478.zip",
  "installPath": "./bin",
  "platforms": [
  "linux"
  },
  {
  "description": "Mono Runtime (macOS)",
  - "url": "https://omnisharpdownload.blob.core.windows.net/ext/mono.osx-4.6.1.zip",
  + "url": "https://omnisharpdownload.blob.core.windows.net/ext/mono.osx-4.8.0.478.zip",
  "installPath": "./bin",
  "platforms": [
  "darwin"
  },
  {
  "description": "Mono Framework Assemblies",
  - "url": "https://omnisharpdownload.blob.core.windows.net/ext/framework-4.6.1.zip",
  + "url": "https://omnisharpdownload.blob.core.windows.net/ext/framework-4.8.0.478.zip",
  "installPath": "./bin/framework",
  "platforms": [
  "darwin",
  },
  {
  "description": "OmniSharp (.NET 4.6 / x86)",
  - "url": "https://omnisharpdownload.blob.core.windows.net/ext/omnisharp-win-x86-1.9-beta22.zip",
  + "url": "https://omnisharpdownload.blob.core.windows.net/ext/omnisharp-win-x86-1.9-beta23.zip",
  "installPath": "./bin/omnisharp",
  "platforms": [
  "win32"
  },
  {
  "description": "OmniSharp (.NET 4.6 / x64)",
  - "url": "https://omnisharpdownload.blob.core.windows.net/ext/omnisharp-win-x64-1.9-beta22.zip",
  + "url": "https://omnisharpdownload.blob.core.windows.net/ext/omnisharp-win-x64-1.9-beta23.zip",
  "installPath": "./bin/omnisharp",
  "platforms": [
  "win32"
  },
  {
  "description": "OmniSharp (Mono 4.6)",
  - "url": "https://omnisharpdownload.blob.core.windows.net/ext/omnisharp-mono-1.9-beta22.zip",
  + "url": "https://omnisharpdownload.blob.core.windows.net/ext/omnisharp-mono-1.9-beta23.zip",
  "installPath": "./bin/omnisharp",
  "platforms": [
  "darwin",
  