Visualize spectrogram of uploaded audio

[LanesGood]

Story

After uploading my audio file, I can see the spectrogram visualization of my uploaded audio

Requirements

• [x] #56
• [x] The spectrogram is rendered in a [grayscale /or/ viridis] colormap (confirm with partners)
• [x] I can click zoom buttons to zoom in and out of the spectrogram, or increase/decrease the pixels per second on the x-axis
• [x] I can click a "fit" button to fit the entire audio file's spectrogram in the width of the viewport
• [x] I can see the start and end times of my uploaded audio
• [ ] #24

[oliverroick]

Closing this ticket. Most of these are done, the ones that aren't have separate tickets.