feat: [SyntaxNode/Tree].ByType (Fixes #644)

Types/Microsoft.CodeAnalysis/SyntaxNode/get_ByType.ps1

@@ -0,0 +1,14 @@
+if (-not $this.'.ByType') {
+    $ByType = [Collections.Generic.Dictionary[Type,Collections.Generic.List[PSObject]]]::new()
+    foreach ($node in $this.FindAll({$true}, $true)) {
+        $nodeType = $node.GetType()
+
+        if (-not $ByType[$nodeType]) {
+            $ByType[$nodeType] = [Collections.Generic.List[PSObject]]::new()
+        }
+        $ByType[$nodeType].Add($node)
+    }
+    Add-Member -InputObject $this -MemberType NoteProperty -Name '.ByType' -Value $ByType -Force
+}
+
+$this.'.ByType'

Types/Microsoft.CodeAnalysis/SyntaxTree/get_ByType.ps1

@@ -0,0 +1,11 @@
+<#
+.SYNOPSIS
+    Gets CSharp AST Nodes by type
+.DESCRIPTION
+    Gets a dictionary of all nodes in a CSharp AST beneath this point, grouped by type.
+.EXAMPLE
+    (Parse-CSharp '"Hello World";').ByType
+#>
+
+
+$this.Root.ByType