build: fix doinst.sh compatibility with installpkg --root (#1446)

- Isolate plugin concerns into `.plg` plugin & api file modifiers instead of the api's
slackware package.

## Summary by CodeRabbit

* **New Features**
* Installation process modularized into package installation,
post-install setup with verification, and service startup with cleanup.
* Added logging and error detection during installation, including
symlink verification.
  * Created required log directory to support service dependencies.
* Integrated nginx service with reload capability triggered by
configuration changes.
* Added automatic patching of nginx configuration and hosts file to
improve security and iframe compatibility.
* Enhanced file modification system to handle side effects and trigger
nginx reloads as needed.

* **Refactor**
* Restructured installation scripts for clarity; setup scripts now
separate steps.
  * Removed legacy installation logic and deprecated related scripts.
  * Enabled hard link addition during package creation.
* Simplified installation scripts by removing conditional branching and
detailed logging.
* Streamlined API environment setup by removing redundant post-install
steps.
* Updated dependency injection to explicitly provide nginx service
token.
  * Improved patch application error reporting with file path details.

* **Chores**
  * Disabled legacy scripts to streamline installation.
  * Removed `.gitignore` to track previously ignored files.
* Updated tests to include new dependencies and relaxed logger
assertions.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

---
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used, see below:
  - https://app.asana.com/0/0/1210661184127051

packages/unraid-shared/src/services/nginx.ts

@@ -0,0 +1,7 @@
+export interface NginxService {
+    /**
+     * Reloads nginx via its rc script
+     * @returns true if the reload was successful, false otherwise
+     */
+    reload(): Promise<boolean>;
+}

packages/unraid-shared/src/tokens.ts

@@ -1,3 +1,4 @@
 export const UPNP_CLIENT_TOKEN = 'UPNP_CLIENT'; 
 export const API_KEY_SERVICE_TOKEN = 'ApiKeyService';
 export const LIFECYCLE_SERVICE_TOKEN = 'LifecycleService';
+export const NGINX_SERVICE_TOKEN = 'NginxService';