* 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>
* Consistent license message for all the go files
* Fixing the last set of unconsistencies with the license headers
* Addressing PR review comments
* Fixing busy.go and busy_test.go license header
* TestGetLicenseFileFromDisk: avoid using fileutils.FindConfigFile
* config: abstract config-related file access, extend memory store
* simplify config validate to avoid file knowledge
* fix relative file tests
* cluster: fix ConfigChanged event
The old and new configurations were swapped when notifying the enterprise code of configuration changes, creating needless instability in propagating config updates across a cluster.
* config/database: ignore duplicates
* test cleanup
* remove unnecessary Save() in test
