MM-43753: Module workspaces (#20113)

* MM-43753: Module workspaces

Move to module workspaces

We make the following changes:
- Remove the vendor directory.
- Dynamically create the go.work file if it doesn't exist.
- Set the MM_SERVER_PATH for enterprise tests.

https://mattermost.atlassian.net/browse/MM-43753

```release-note
NONE
```

* Fix missing reference to MM_SERVER_PATH

```release-note
NONE
```

* Update test to add another nested dir

```release-note
NONE
```

* Have separate script to create go.work file

```release-note
NONE
```

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

utils/fileutils/fileutils_test.go

@@ -100,10 +100,10 @@ func TestFindFile(t *testing.T) {
 					filePathResolved,
 				},
 				{
-					fmt.Sprintf("%s: can't find from four nesting levels deep", fileName),
+					fmt.Sprintf("%s: quadruple-nested subdirectory of containing directory", fileName),
 					&tmpDir5,
 					fileName,
-					"",
+					filePath,
 				},
 			}...)
 		}