ComboBox: Add name prop

[FallingSnow]

Bug Report

• Package version(s): 6.18.0
• Browser and OS versions: Firefox Nightly 62.0a1, Linux 64bit

Priorities and help requested:

Are you willing to submit a PR to fix? No

Requested priority: Low

Products/sites affected: -

Describe the issue:

ComboBoxes do not pass the name property to the inner input. This impares it's usage in forms, especially with HTML5 Formdata.

Actual behavior:

No name property on the inner input tag.

Expected behavior:

Matching name property on the inner input tag.

[mikewheaton]

I also can't see a way to provide a name attribute to the input that ComboBox renders. It would be useful to have a prop specifically for this purpose or to be able to pass in a full set of props to the TextField within.

[micahgodbolt]

Adding this to #6030, which is our meta issue for the consolidation of dropdown and comobobox