[Filing] Upload - Adjust when we render the 'Unable to continue' messaging

[meissadia]

Close #766

Changes

• Moves the error Alert re: not being ready to save and continue down to the bottom of the page
  • Shows/hides this alert as demonstrated below

Demos

Scenario 1 - New upload

Scenario.1.-.New.upload.mov

Scenario 2 - Existing upload

Scenario.2.-.Existing.upload.mov

Scenario 3 - Error uploading

Scenario.3.-.Error.upload.mov

Scenario 4 - Ready to save and continue

Scenario.4.-.Save.and.continue.mov

[natalia-fitzgerald]

@meissadia

• The error alert message for any time a user clicks the "Save and continue" button without completing the requirements for the step should be: "File upload and validation checks must be completed to save and continue."
• This error alert should be positioned at the bottom of the page under "Go back" and "Save and continue"
• In the example you show here the changes to the implementation would be to update the error alert text and move the error alert box to the bottom of the page as shown in the mock-up.

[meissadia]

@natalia-fitzgerald Updated demo videos to show current functionality.

[billhimmelsbach]

Hey @natalia-fitzgerald, mind taking a look at these changes in the videos above / on the preview site?

[natalia-fitzgerald]

@meissadia
As a part of this PR will you add the alert to the Resolve errors and Review warnings pages? In order to create consistency across the alerts on all of these pages can you change the text to paragraph (instead of H4) and include a period? This is what we do on Resolve errors and Review warnings for this alert.

[shindigira]

Added accessibility notice

[shindigira]

@meissadia As a part of this PR will you add the alert to the Resolve errors and Review warnings pages? In order to create consistency across the alerts on all of these pages can you change the text to paragraph (instead of H4) and include a period? This is what we do on Resolve errors and Review warnings for this alert.

Would you like a field level alert instead?

[natalia-fitzgerald]

@shindigira
For now let's keep the form-level alert (I did consider field-level but landed on form-level for visual prominence and because it does apply to the whole form...although typically a form-level alert would sit above, not below, the form). The styling should be standard paragraph style with a period at the end of the sentence.

• Regular weight (400)
• 16px
• Avenir Next

[ojbravo]

LGTM!