Remove 'WebView2' package dependency

[Sergio0694]

Description

This PR is a workaround for a bug in the PRI files for the *.WinUI packages, caused by the WebView2 package:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<PriInfo>
  <ResourceMap name="ComputeSharp.D2D1.WinUI" version="1.0" primary="true">
    <Qualifiers/>
    <ResourceMapSubtree name="Files">
      <ResourceMapSubtree name="ComputeSharp.D2D1.WinUI">
        <ResourceMapSubtree name="runtimes">
          <ResourceMapSubtree name="win-arm64">
            <ResourceMapSubtree name="native">
              <NamedResource name="WebView2Loader.dll" uri="ms-resource://ComputeSharp.D2D1.WinUI/Files/ComputeSharp.D2D1.WinUI/runtimes/win-arm64/native/WebView2Loader.dll">
                <Candidate type="Path">
                  <Value>ComputeSharp.D2D1.WinUI\runtimes\win-arm64\native\WebView2Loader.dll</Value>
                </Candidate>
              </NamedResource>
            </ResourceMapSubtree>
          </ResourceMapSubtree>
          <ResourceMapSubtree name="win-x64">
            <ResourceMapSubtree name="native">
              <NamedResource name="WebView2Loader.dll" uri="ms-resource://ComputeSharp.D2D1.WinUI/Files/ComputeSharp.D2D1.WinUI/runtimes/win-x64/native/WebView2Loader.dll">
                <Candidate type="Path">
                  <Value>ComputeSharp.D2D1.WinUI\runtimes\win-x64\native\WebView2Loader.dll</Value>
                </Candidate>
              </NamedResource>
            </ResourceMapSubtree>
          </ResourceMapSubtree>
          <ResourceMapSubtree name="win-x86">
            <ResourceMapSubtree name="native">
              <NamedResource name="WebView2Loader.dll" uri="ms-resource://ComputeSharp.D2D1.WinUI/Files/ComputeSharp.D2D1.WinUI/runtimes/win-x86/native/WebView2Loader.dll">
                <Candidate type="Path">
                  <Value>ComputeSharp.D2D1.WinUI\runtimes\win-x86\native\WebView2Loader.dll</Value>
                </Candidate>
              </NamedResource>
            </ResourceMapSubtree>
          </ResourceMapSubtree>
        </ResourceMapSubtree>
      </ResourceMapSubtree>
    </ResourceMapSubtree>
  </ResourceMap>
</PriInfo>

Those WebView2Loader.dll items should not be there, and will cause all consumer projects to fail to build.

This PR simply removes all the WebView2 package references entirely, so the issue can't happen at all.