FE: NMS-17004: Update the login events item in Usage Stats, add link to download CSV file

[Shahbaz-dataq]

Description

A new item, “CSV output of Login events for the past 60 days”, has been added to the usage stats list.

The “Latest Value” column will contain Base64-encoded file contents.

Update the column to display a download link labeled “Download CSV file”. The link should decode the Base64 content and trigger the file download.

The implementation should be generic, based on the datatype value (file|csv) provided in the metadata.

If the datatype starts with "file", split it using | to extract the file type (e.g., csv in this case) and handle the file appropriately.

Metadata:

{
"key": "loginsPast60Days",
"name": "CSV output of Login events for the past 60 days",
"description": "CSV output containing the date, username login events for the past 60 days",
"datatype": "file|csv"
}

External References

• Jira (Issue Tracker): https://opennms.atlassian.net/browse/NMS-17004