Dataset Info Attributes Section

[BryonLewis]

resolves #401

• Adds to the DatasetInfo.vue context panel an expandable section for Attribute information
• It is only visible when a track is selected
• Provides track and detection attributes under their own expandable sections
• Detection attributes have an option for stickiness (displaying the last non-empty value for the detection attribute regardless of the current frame)
• Info icons for each attribute show type and any predefined values.