Fdc3 - Enable Fdc3 as an optional feature

[lilla28]

Changes:

• Added Directory.Build.props files
• Moved composeui-fdc3 js implementation under fdc3/js folder
• Renamed PreloadFdc3 to ResourceNames
• Added MessagingRouter.Client to the solution for building the project
• Refactored namespaces in Shell and Shell.Tests projects,
• Added Fdc3Options to check if it is enabled from appsettings.json
• Renamed Fdc3DesktopAgentConfig to Fdc3DesktopAgentBuilder
• Modified ServiceCollectionExtensions in Fdc3DesktopAgent
• Added ServiceCollection extension method for DesktopAgent to check the Fdc3Options and inject DesktopAgent if that is enabled from config
• Added TODO to ResourceReader that we should move this utility to a new project later under src/shared/dotnet
• Added missing headers
• Fixing DesktopAgent.Tests's DesktopAgent setup
• Removed WithUserChannel from DesktopAgent's Fdc3DesktopAgentBuilder
• Removed internal BuilderActions property from Fdc3Options

[codecov]

Codecov Report

Merging #347 (1b528ec) into main (605c56e) will increase coverage by 2.70%.
The diff coverage is 53.19%.

@@            Coverage Diff             @@
##             main     #347      +/-   ##
==========================================
+ Coverage   74.58%   77.29%   +2.70%     
==========================================
  Files         155      156       +1     
  Lines        5474     5302     -172     
  Branches      233      233              
==========================================
+ Hits         4083     4098      +15     
+ Misses       1390     1203     -187     
  Partials        1        1              

Files Changed	Coverage Δ
...dc3/js/composeui-fdc3/src/ComposeUIDesktopAgent.ts	83.00% <ø> (ø)
...poseui-fdc3/src/infrastructure/ComposeUIChannel.ts	100.00% <ø> (ø)
...oseui-fdc3/src/infrastructure/ComposeUIListener.ts	92.20% <ø> (ø)
...omposeui-fdc3/src/infrastructure/ComposeUITopic.ts	93.10% <ø> (ø)
.../infrastructure/messages/Fdc3FindChannelRequest.ts	100.00% <ø> (ø)
...structure/messages/Fdc3GetCurrentContextRequest.ts	100.00% <ø> (ø)
src/shell/dotnet/Shell/App.xaml.cs	0.00% <0.00%> (ø)
...tnet/Shell/ImageSource/DefaultImageSourcePolicy.cs	0.00% <ø> (ø)
.../Shell/ImageSource/EnvironmentImageSourcePolicy.cs	0.00% <0.00%> (ø)
...ll/dotnet/Shell/ImageSource/ImageSourceProvider.cs	0.00% <ø> (ø)
... and 15 more

... and 8 files with indirect coverage changes