* Add 'ImplicitUsings=true' to all the templates.
* Make the implicit global namespaces C#-only.
* Add the implicit global namespaces to the 'Using' itemgroup instead of the
'Import' itemgroup.
* Make sure the global namespaces are set from AutoImport.props, so that the
user may remove any global namespace they don't want in their project file
(by doing something like: `<Using Remove="Foundation" />`)
Ref: https://github.com/dotnet/sdk/issues/19521
Ref: https://github.com/dotnet/sdk/issues/19793
Fixes https://github.com/xamarin/xamarin-macios/issues/12457.
When we're using 'open' to launch apps, we need to use '--args ...' to pass any additional argument to the app, because otherwise 'open' will try to open those arguments as if they were files:
```
$ open "/Applications/Sublime Text.app" helloworld
The file /Users/rolf/test/helloworld does not exist.
```
(and doesn't launch Sublime Text).
while this works:
```
$ open "/Applications/Sublime Text.app" --args helloworld
```
in that it opens Sublime Text.
It's also possible to not append any other arguments, so this:
```
$ open "/Applications/Sublime Text.app" --args
```
while it looks weird, it works just fine.
Ref: https://github.com/dotnet/sdk/issues/18437
* [dotnet] Normalize run target assembly path on the Run target for Mac Catalyst
* Use TargetPath instead of OutputPath for resolving assembly output directory
NuGet doesn't support preserving the executable bit for files in *.nupkgs
(which are just zip files), so .NET implemented a [temporary
workaround](https://github.com/dotnet/sdk/pull/17299) for workload installs,
where they hardcoded files that should be executable.
This isn't really sustainable, and they'll remove their workaround, so we need
to use their supported method of specifying the file permissions: a
data/UnixFilePermissions.xml file.
Fixes https://github.com/xamarin/xamarin-macios/issues/11860.
Rolf Bjarne Kvinge
Yusuke Yamada