Fix members search with multiple words

📖 What does this MR do?

Related to #328667 (closed)

Currently group/project member searches with multiple words do not work correctly, it only searches for the last word. This is because GlFilteredSearch splits up the search term by spaces into multiple "tokens". From what I have found in the codebase it appears the fix for this is to gather up all of the search "tokens" and concatenate them into one search term.

We use this technique in the following places:

• app/assets/javascripts/issues_list/components/issuables_list_app.vue#L350
• ee/app/assets/javascripts/boards/components/epic_filtered_search.vue#L114
• ee/app/assets/javascripts/integrations/jira/issues_list/components/jira_issues_list_root.vue#L166

💻 Local testing

1. Create a group or project
2. Navigate to group/project -> "Members"
3. Type a term with two or more words in the search bar

📷 Screenshots

View	Before	After
Group members (search term: cassie frami)
Project members (search term: mose haley)

🚦 Does this MR meet the acceptance criteria?

Does this MR meet the acceptance criteria?

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