Lower WindowsAppSDK min version to be 17763

[michael-hawker]

Fixes #233

This is needed to lower the min version of the Windows Community Toolkit to match the min version of the WindowsAppSDK 1.x releases of 17763 (instead of 18362 as the original Project Reunion releases were). See issue for more details.

Built package locally (added instructions to readme) and tested in a new Windows App SDK 1.1.x project targeting 17763. Example in readme worked without issue.

Commented out designtools dlls from WinUI nuspec as wouldn't build (and no designer in WinUI, so assume that's why they didn't work?)

FYI @DVaughan @azchohfi, know you've moved to other work now, but if you can spare a minute for a quick glance, would be great!

[DVaughan]

I'm not sure about the design-time assembly failures. In the absence of a WinUI designer I would have thought that those would be ignored. There might be something that needs disabling in the interim. Adding @mgoertz-msft & @bhavyaus

[mgoertz-msft]

The designtools DLLs are used by the XAML editor as well for things like EditorBrowsable, etc. Given that they built successfully before we should probably figure out why they don't anymore.

[michael-hawker]

I do see now comparing in NuGet Package Explorer that the DesignTools assemblies were there:

So, I'm not sure why that was failing locally for me for them to be found during the build. I'll try taking another look.

[michael-hawker]

Alright I was able to build it all locally:

Not too sure what my issue was the first time. I guess something in my environment hadn't built the other part. I did a git clean, and rebuilt and things worked.

Would be good to document the msbuild step that VS is doing so it can be built entirely on the commandline as well vs. having to build all in VS.

Will commit here in a minute with the uncommenting of the nuspec file.

[mgoertz-msft]

Should this also be /p:TimestampPackage=true?