ci: Introduce no-plain-errors lint rule for BE packages (no-changelog) (#7961)

## Summary
Require `ApplicationError` or its child classes instead of plain `Error`
in BE packages. This ensures the error will be normalized when reported
to Sentry, if applicable.

Follow-up to:
https://github.com/n8n-io/n8n/pulls?q=is%3Apr+is%3Aclosed+applicationerror

...

#### How to test the change:
1. ...


## Issues fixed
Include links to Github issue or Community forum post or **Linear
ticket**:
> Important in order to close automatically and provide context to
reviewers

...


## Review / Merge checklist
- [ ] PR title and summary are descriptive. **Remember, the title
automatically goes into the changelog. Use `(no-changelog)` otherwise.**
([conventions](https://github.com/n8n-io/n8n/blob/master/.github/pull_request_title_conventions.md))
- [ ] [Docs updated](https://github.com/n8n-io/n8n-docs) or follow-up
ticket created.
- [ ] Tests included.
> A bug is not considered fixed, unless a test is added to prevent it
from happening again. A feature is not complete without tests.
  >
> *(internal)* You can use Slack commands to trigger [e2e
tests](https://www.notion.so/n8n/How-to-use-Test-Instances-d65f49dfc51f441ea44367fb6f67eb0a?pvs=4#a39f9e5ba64a48b58a71d81c837e8227)
or [deploy test
instance](https://www.notion.so/n8n/How-to-use-Test-Instances-d65f49dfc51f441ea44367fb6f67eb0a?pvs=4#f6a177d32bde4b57ae2da0b8e454bfce)
or [deploy early access version on
Cloud](https://www.notion.so/n8n/Cloudbot-3dbe779836004972b7057bc989526998?pvs=4#fef2d36ab02247e1a0f65a74f6fb534e).

packages/cli/src/environments/sourceControl/sourceControlExport.service.ee.ts

@@ -6,7 +6,7 @@ import {
 	SOURCE_CONTROL_TAGS_EXPORT_FILE,
 	SOURCE_CONTROL_WORKFLOW_EXPORT_FOLDER,
 } from './constants';
-import type { ICredentialDataDecryptedObject } from 'n8n-workflow';
+import { ApplicationError, type ICredentialDataDecryptedObject } from 'n8n-workflow';
 import { writeFile as fsWriteFile, rm as fsRm } from 'fs/promises';
 import { rmSync } from 'fs';
 import { Credentials, InstanceSettings } from 'n8n-core';
@@ -138,7 +138,7 @@ export class SourceControlExportService {
 				})),
 			};
 		} catch (error) {
-			throw Error(`Failed to export workflows to work folder: ${(error as Error).message}`);
+			throw new ApplicationError('Failed to export workflows to work folder', { cause: error });
 		}
 	}
 
@@ -168,7 +168,9 @@ export class SourceControlExportService {
 				],
 			};
 		} catch (error) {
-			throw Error(`Failed to export variables to work folder: ${(error as Error).message}`);
+			throw new ApplicationError('Failed to export variables to work folder', {
+				cause: error,
+			});
 		}
 	}
 
@@ -208,7 +210,7 @@ export class SourceControlExportService {
 				],
 			};
 		} catch (error) {
-			throw Error(`Failed to export variables to work folder: ${(error as Error).message}`);
+			throw new ApplicationError('Failed to export variables to work folder', { cause: error });
 		}
 	}
 
@@ -280,7 +282,7 @@ export class SourceControlExportService {
 				missingIds,
 			};
 		} catch (error) {
-			throw Error(`Failed to export credentials to work folder: ${(error as Error).message}`);
+			throw new ApplicationError('Failed to export credentials to work folder', { cause: error });
 		}
 	}
 }