housekeeping: Update the directory.build.props

[glennawatson]

• Updating the directory.build.props to have all the latest NuGet packages
• Removed the base directory ones now, without the samples it's no longer as needed
• To allow for easier debugging for android maintainers, using full debug type on that platform.

[codecov]

Codecov Report

Merging #2082 into master will decrease coverage by 0.02%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #2082      +/-   ##
==========================================
- Coverage   60.08%   60.05%   -0.03%     
==========================================
  Files         117      117              
  Lines        4464     4464              
  Branches      639      639              
==========================================
- Hits         2682     2681       -1     
  Misses       1611     1611              
- Partials      171      172       +1

Impacted Files	Coverage Δ
src/ReactiveUI/RxApp.cs	81.57% <0%> (-1.32%)	⬇️

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