Auto-focus "Project" selector when adding new issue to group-level board

When creating an issue in a group-level board, auto-focus the project search text field.

UI Flow

Prerequisites

• Your group has an issue board configured
• Your group has at least one project

Actual Flow

1. Navigate to the group's issue board

2. Click + in the top right of one of the board's lists

   A "new issue" card is engaged. The Title text field is auto-focused

3. Type an issue title

4. Click the Project input

5. Click the Search projects text field

   A search dialog appears.

6. Type a project name

7. Click an entry in the drop-down list

Expected Flow

1. Navigate to the group's issue board

2. Click + in the top right of one of the board's lists

   A "new issue" card is engaged. The Title text field is auto-focused

3. Type an issue title

4. Click the Project input

   A search dialog appears. The Search projects text field is auto-focused (added)

5. Click the Search projects text field (removed)

6. Type a project name

7. Click an entry in the drop-down list

Implementation plan

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We will need to change ee/app/assets/javascripts/boards/components/group_select.vue. We will need to add ref to our GlSearchBoxByType and invoke .focusInput on ref when relevant gl-dropdown is triggered.

We will need to update tests accordingly