Added toggleterm plugin and remap for it

after/plugin/toggleterm.lua

@@ -0,0 +1,9 @@
+local status, toggleterm = pcall(require, "toggleterm")
+if not status then
+    return
+end
+
+toggleterm.setup {
+    shell = "pwsh.exe -nologo",
+    start_in_insert = true,
+}