Load server or client args from synergy-config.toml (#7467)

* Load args from .toml file

* Remove .toml files

* Handle _ arg as no key

* Remove dotenv-cpp

* Treat special last arg specially

* Improve restart warning

* Remove rogue include

* Move TOML config loader to new class

* Merge config files into one

* Add override to virtual functions

* Tidy up App decl and add missing overrides

* Add comments to organize function types

* Fixed: config.h doesn't work on Windows

* Move var position

* Improve includes in app classes

* Update ChangeLog

* Restore position of configure_file call

* Remove new entries in .in file

.gitignore

@@ -9,6 +9,7 @@ Brewfile.lock.json
 /.cache
 
 # typical developer-created files
+synergy-config.toml
 .vscode
 .DS_Store
 *.code-workspace