We currently have three components that don't enable the "Continue" button by default which is flagged as a bad pattern in the "usability" feedback section of our Accessbility report:

1. FindProperty (two pages - select & map)
2. DrawBoundary (two pages - map & upload)
3. FileUpload

These changes address enabling the continue button for all "upload" instances. I'll continue to address the map & select instances in a followup PR (see #3022).

Testing:

• DrawBoundary
  • When you switch to the upload page the "continue" button should always be enabled now
  • If you click it before uploading, you should see an error wrapper around the upload preventing you from proceeding
  • If you upload a file, you can proceed successfully
• FileUpload
  • "Continue" should be enabled by defualt
  • If you click before uploading, or while a large file is still loading, you should see an error wrapper preventing you from proceeding
  • If you upload a file, you can proceed successfully