Automation of Keycloak Security Vulnerability reports

[abstractj]

This PR is a MVP to address the requirements present at https://github.com/keycloak/keycloak-security-team/issues/3

Create a .env file with the following configuration:

# --- Google / Gmail Config ---
GMAIL_CLIENT_ID=
GMAIL_CLIENT_SECRET=
GMAIL_REFRESH_TOKEN=
GMAIL_USER_EMAIL=

# Note: These are hardcoded in application.properties as you requested,
# but if you wanted to override them locally, you could use:
EMAIL_TARGET_SECALERT=