Implement uninstall tool command.

This commit implements the `uninstall tool` command.

The `uninstall tool` command is responsible for uninstalling global tools that
are installed with the `install tool` command.

This commit heavily refactors the ToolPackage and ShellShim namespaces to
better support the operations required for the uninstall command.

Several string resources have been updated to be more informative or to correct
oddly structured sentences.

This commit also fixes `--version` on the install command not supporting ranges
and wildcards.

Fixes #8549.

Issue #8485 is partially fixed by this commit (`--prerelease` is not yet
implemented).

src/dotnet/ToolPackage/ToolPackageStore.cs

@@ -0,0 +1,42 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using Microsoft.Extensions.EnvironmentAbstractions;
+
+namespace Microsoft.DotNet.ToolPackage
+{
+    internal class ToolPackageStore : IToolPackageStore
+    {
+        public ToolPackageStore(DirectoryPath root)
+        {
+            Root = root;
+        }
+
+        public DirectoryPath Root { get; private set; }
+
+        public IEnumerable<IToolPackage> GetInstalledPackages(string packageId)
+        {
+            if (packageId == null)
+            {
+                throw new ArgumentNullException(nameof(packageId));
+            }
+
+            var packageRootDirectory = Root.WithSubDirectories(packageId);
+            if (!Directory.Exists(packageRootDirectory.Value))
+            {
+                yield break;
+            }
+
+            foreach (var subdirectory in Directory.EnumerateDirectories(packageRootDirectory.Value))
+            {
+                var version = Path.GetFileName(subdirectory);
+                yield return new ToolPackageInstance(
+                    this,
+                    packageId,
+                    version,
+                    packageRootDirectory.WithSubDirectories(version));
+            }
+        }
+    }
+}