Jenkins JX Resources Plugin missing permission check

Jenkins jx-resources Plugin did not perform permission checks on a method implementing form validation. This allowed users with Overall/Read access to Jenkins to connect to an attacker-specified Kubernetes server and obtain information about an attacker-specified namespace. Doing so might also leak service account credentials used for the connection. Additionally, it allowed attackers to obtain the value of any attacker-specified environment variable for the Jenkins controller process.

Additionally, this form validation method did not require POST requests, resulting in a cross-site request forgery vulnerability.

This form validation method now requires POST requests and Overall/Administer permissions.