Add Devcontainers to allow easy use of the AF repo from github codespaces (#1224)

* Add dev containers

* Add workspace folder and cs dev extension

* Try other workspace folder format

* Add default solution.

* Move default solution to settings.json

* Fix repo open

* Remove duplicate python codespace and rename folder

* Add recommended C# extensions and a default build task

* Add vscode icons extension by default

* Add python setup and customizations, plus ai studio for all

* Add bash command

* Try running devsetup from workspace folder

* Remove echo and cd

* Change workspace mount

* Change dotnet workspace name

* Revert workspacemount addition

* Try workspace mount to root

* remove trailing slash

* Try workspacefolder with var

* Revert to original approach

* Modify dev containers to work in main repo.

* Remove trailing comma

* Apply suggestion from @Copilot

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

---------

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

dotnet/.vscode/extensions.json

@@ -0,0 +1,5 @@
+{
+    "recommendations": [
+        "ms-dotnettools.csdevkit"
+    ]
+}

dotnet/.vscode/settings.json

@@ -0,0 +1,4 @@
+{
+    "dotnet.defaultSolution": "agent-framework-dotnet.slnx",
+    "git.openRepositoryInParentFolders": "always"
+}

dotnet/.vscode/tasks.json

@@ -0,0 +1,15 @@
+{
+	"version": "2.0.0",
+	"tasks": [
+		{
+			"type": "dotnet",
+			"task": "build",
+			"group": {
+				"kind": "build",
+				"isDefault": true
+			},
+			"problemMatcher": [],
+			"label": "dotnet: build"
+		}
+	]
+}