Autofill should automatically move cursor to first entry when adding a new record

[alexwykoff]

Test Plan:

#8510 (comment)

1. Open browser and type about:autofill
2. Click on Add Address or Add Credit Card
3. Cursor will focus on first input field

Original issue description

• Did you search for similar issues before submitting this one?
  Yes

• Describe the issue you encountered:
  When adding a record, I found that I had to click in the modal first to edit values.

• Platform (Win7, 8, 10? macOS? Linux distro?):
  Tested on OS X

• Brave Version (revision SHA):
  0.14.2 (f07c142)

• Steps to reproduce:

  1. visit about:autofill
  2. add a record

• Actual result:
  The cursor is not in any available field

• Expected result:
  The cursor should move to the first field and save the user a click

• Will the steps above reproduce in a fresh profile? If not what other info can be added?

• Is this an issue in the currently released version?

• Can this issue be consistently reproduced?

• Extra QA steps:
  1.
  2.
  3.

• Screenshot if needed:

• Any related issues:

[kumarrishav]

I will be happy to take this bug. This will be my first contribution to brave. Currently i am setting up the env and building brave from source. It will be great to have some pointer to start with.