feat: Enable DotnetToolMode option when creating nupkg

[filzrev]

What's included in this PR

• Add MSBuild target to move templates folders to TargetFramework independent path.
• Add MSBuild target to enable DotnetToolMode when creating nupkg with dotnet pack command.
• Fix dotnet template command error when running with DotnetToolMode.

This PR intended to fix #8691 issue.

What's tested manually on my local environment

dotnet pack command

• docfx.runtimesettings.json contains "Docfx.DotnetToolMode": true entry.
• TargetFramework dependent templates(at tools/{$(TargetFramework)}/any/templates) are removed from package.
• Template files are re-located to TargetFramework independent path (templates/**).
• Install generated nupkg as .NET tools. and basic command works as expected.

dotnet publish command.

• templates directory structure is not changed.
• docfx.runtimesettings.json is not modified.

[codecov]

Codecov Report

Patch and project coverage have no change.

Comparison is base (100d234) 77.59% compared to head (f46fb23) 77.59%.
Report is 3 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #9115   +/-   ##
=======================================
  Coverage   77.59%   77.59%           
=======================================
  Files         592      592           
  Lines       24604    24607    +3     
=======================================
+ Hits        19091    19094    +3     
  Misses       5513     5513           

Files Changed	Coverage Δ
src/docfx/Models/TemplateCommand.cs	0.00% <0.00%> (ø)

... and 2 files with indirect coverage changes

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[yufeih]

This is Epic @filzrev !