127: Add download links to listen page

[rpeterman-gp]

Closes #127 Closes #155

• add download link to playlist items
• add download link to episode header
• fix clipping of title text on episode view
• add fileSize to audio data
• add download prop to icon button component
• move cc button between progress bar and settings button
• improve layout of floating elements:
  • player
  • mobile playlist header
  • mobile episode header

To Review

• [x] Checkout Branch.
• [x] Run asdf install.
• [x] Run yarn.
• [x] Run yarn dev.
• [ ] Go to http://localhost:4300/listen?uf=https%3A%2F%2Fpublicfeeds.net%2Ff%2F5043%2Ffeed-rss.xml

...then...

• [x] Ensure download link on playlist items downloads file when clicked.
• [x] Click title of an episode.
• [x] Ensure download link on episode view downloads file when clicked.
• [x] Resize window to mobile width. Ensure episode header content resizes responsively and no longer overflows right edge on really thin mobile sizes (Galaxy Z Fold candy bar size).
• [x] Go to http://localhost:4300/listen?uf=https%3A%2F%2Fkala.farski.com%2Fearhustlesq.xml&ac=EBCF00&ge=prx_59_df430720-ef2b-4648-8d6c-2060e7efbe6c
• [x] Note CC button moved to menu next to progress bar.
• [ ] Ensure episode header with nav links on episode with transcripts looks good.
• [ ] Go to http://localhost:4300/listen?uf=http%3A%2F%2Ffeeds.kera.org%2FKERA-Think&ge=prx_140_2c648e10-5980-48ab-8332-9045853db9fe
• [ ] Ensure title in top bar is no longer clipping.

[rpeterman-gp]

@brandonhundt That status bar is the title of the VIEWED episode, not what is currently playing. Users can view an episode while another is playing in the player. Where exactly are you thinking of folding the back button into? Not clear on what you are calling the "heading".

Anyway, any solution I can think of would require more than just some small css or markup tweaks. This change should probably be its own ticket.