feat: add common functions library and resend welcome email script

[printminion-co]

This commit introduces a new common.sh library that provides standardized logging, error handling, and OCC command execution functions for IONOS admin tools. Additionally, a new script resend-welcome-mail-user.sh is added to facilitate resending welcome emails to specific Nextcloud users, complete with argument parsing and help documentation.

ubuntu@nc-dev-container:/var/www/html$ ./IONOS/admin-tools/resend-welcome-mail-user.sh g1user1 --quiet
ubuntu@nc-dev-container:/var/www/html$ echo $?
0
ubuntu@nc-dev-container:/var/www/html$ ./IONOS/admin-tools/resend-welcome-mail-user.sh g1user1
[INFO] Starting resend-welcome-mail-user.sh
[INFO] Checking if user 'g1user1' exists...
[INFO] Resending welcome email to user: 'g1user1'
[INFO] Executing: php /var/www/html/occ user:welcome g1user1
[SUCCESS] Welcome email sent to user: 'g1user1'
[SUCCESS] Operation completed successfully
ubuntu@nc-dev-container:/var/www/html$ echo $?
0
ubuntu@nc-dev-container:/var/www/html$ ./IONOS/admin-tools/resend-welcome-mail-user.sh john.doe
[INFO] Starting resend-welcome-mail-user.sh
[INFO] Checking if user 'john.doe' exists...
[FATAL] User 'john.doe' does not exist

[Copilot]

Pull request overview

This PR introduces a reusable shell script library and administrative tooling for Nextcloud operations. It establishes standardized patterns for logging, error handling, and OCC command execution across IONOS admin tools.

Key Changes:

• Created common.sh library with logging functions, OCC command wrappers, and validation utilities
• Added resend-welcome-mail-user.sh script to resend welcome emails with comprehensive argument parsing
• Documented the admin tools framework, conventions, and usage patterns in README.md

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
admin-tools/common.sh	Provides shared logging, error handling, and OCC command execution functions for admin scripts
admin-tools/resend-welcome-mail-user.sh	Implements welcome email resending with standardized CLI options and validation
admin-tools/README.md	Documents the admin tools framework, script conventions, and usage examples

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated no new comments.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated no new comments.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[dsteininger86]

review OK