Steam no EAC launch + fix Epic launch (#172)

* Refactor LaunchManager for no EAC via Steam on Linux

* Add Microsoft.Extensions.Logging to fix Windows build

* No EAC via Steam on Windows

Bump version to v5.0.0-rc.15.

* Refactor Epic launch: read path and auth from log

Delete old launch log before reading and launch the game directly
via its executable path instead of wrapping with cmd.exe.

* Convert Windows launch utilities to static classes

Move WinProcArgs and WinReadLog into the LaunchManager directory.
Rename ProcessCommandLine to ProcArgs.
Rename WinReadLog to ReadLog and make it static.
Update all references.

* Remove redundant platform check in Steam path

* Permit already-running Rocket League on Epic launch

Improve argument parsing to avoid false positives from empty command
lines
Downgrade argument retrieval failure log from Error to Warning

* Automatically launch Steam if not running before launching RL

* Extra sleep for Steam launch and consistent launch logging

* Formatting

---------

Co-authored-by: NicEastvillage <nicoesterby@gmail.com>

Author: VirxEC

RLBotCS/Main.cs

@@ -10,7 +10,7 @@
 if (args.Length > 0 && args[0] == "--version")
 {
     Console.WriteLine(
-        "RLBotServer v5.0.0-rc.14\n"
+        "RLBotServer v5.0.0-rc.15\n"
             + $"Bridge {BridgeVersion.Version}\n"
             + "@ https://www.rlbot.org & https://github.com/RLBot/core"
     );