ARC-2723 add share modal

[rachellerathbone]

What's in this PR?
Added onClick event to open a modal for the share page button.

Why
So Jira admins can share a link to the global page with their Jenkins admin.

In the following recording:

• I click the share page button which opens the modal
• I click copy to clipboard and see a confirmation
• I copy the contents to a Confluence page (demo purposes)
• I show that there are 2 people with access to the jira site: admin Rachelle and non-admin Rachelle 🙃
• Non Jira admin Rachelle pastes the link and is able to view the global page (this will only work in dev atm coz it's deployed there... maybe stg too, I can't remember 🤷 )

Screen.Recording.2023-12-11.at.7.43.41.pm.mov

Added feature flags
always the same

Affected issues
ARC-2729

How has this been tested?
Locally and unit tests

What's Next?
Merge many many PRs so @joshkay10 doesn't have to wrap up all my work next week? 🤔

[rachellerathbone]

Wrong issue key in branch name