JIRA Issue Integration - Allow Multiple Project Keys
### Problem
The current JIRA Issue Integration allows for a single Jira project key to be entered on the project integration level. For certain mono repositories, we manage a single code base with multiple JIRA projects.
Therefore we should support the customer setups of 1 GitLab Project -> n Jira Project.
### Proposed solution
Users should be able to select a specific Jira project as a filter to the index and view issues of a particular Jira project at a time.
Integration should remember user's last filter option value so they don't keep resetting it.
Add a filter option for "all" meaning a merged index view of all project keys configured for the integration.
### Technical considerations
Currently Jira issues integration is coupled with vulnerabilities creation - they share the `Jira issue key` field. We could allow multiple keys for the issues integration and if user wants to create vulnerabilities, they need to specify which exact project key they want to use.
This should go along with customer request: "Regarding creating a Jira issue for a vulnerability, customer would like the option to create Jira issues in multiple projects."
<!-- triage-serverless v3 PLEASE DO NOT REMOVE THIS SECTION -->
*This page may contain information related to upcoming products, features and functionality.
It is important to note that the information presented is for informational purposes only, so please do not rely on the information for purchasing or planning purposes.
Just like with all projects, the items mentioned on the page are subject to change or delay, and the development, release, and timing of any products, features, or functionality remain at the sole discretion of GitLab Inc.*
<!-- triage-serverless v3 PLEASE DO NOT REMOVE THIS SECTION -->
epic