Fix #27891: Show full instrument description in tooltip when truncated, for consistent accessibility

[mugolnik]

Resolves: #27891

Summary

This PR allows for the full descriptions of instruments to remain accessible to users even in the event that their original descriptions became truncated. In order to avoid crowding the description text, it also enforces a maximumLineCount of 2, as decided in the linked report.

Specifics

As discussed, the targeted solution for this behavior was to expose a tooltip on hover of the description text. However, this tooltip should only show up if the text is truncated after taking up both lines. As far as I know, QML does not provide a native flag for detecting multi-line text truncation. Therefore this PR implements the isTruncated property:

isTruncated: Number of text lines is equal to the maximumLineCount (2) AND the contentWidth exceeds the width

This allowed for pretty good truncation state tracking (note I specified a buffer of 11 here to handle some inconsistencies, where this was the largest difference I observed when manually testing).

Then, using this property, the description text can be hovered over and if truncated a tooltip (as shown in the attachments) will appear below as requested.

Testing

• Tested this locally, where the tooltip would be exposable only if the description was truncated and otherwise would not be.
• Ran ctests, all passing except for an unrelated audio-specific one.

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