Format phone numbers for PhoneForm initial value

[aduth]

Extracted from: #5619

Why:

• Fixes an issue where if the phone number is used in a PhoneInputComponent (in LG-5333, and after LG-5399), the intl-tel-input library could have trouble parsing the country of an arbitrary, user-entered number value, resulting in a scenario where the flag dropdown appears as an empty gray box.
• Presumably it is easier to read a nicely-formatted phone number than a string of 6-14 numbers (cc @anniehirshman-gsa)
• It matches how the number is actually saved and sent with the attributes bundle, allowing a user to make corrections if they spot an issue
• It matches the behavior where a user's existing phone number automatically pre-fills the input

Screenshots:

Screenshots taken with revisions in #5619 to use PhoneInputComponent on IAL2 address verification step.

Before	After

[zachmargolis]

LGTM

[anniehirshman-gsa]

LGTM! Do the parentheses and dashes automatically appear when the user types a numeric input?

[aduth]

LGTM! Do the parentheses and dashes automatically appear when the user types a numeric input?

The changes here only affect the initial page load. After page load, it behaves the same as phone inputs behave everywhere else ("add phone", hybrid step), which doesn't auto-format the text in any way, except when switching from one country to another.

Is that something we'd want? Might be worth a ticket to implement.

[anniehirshman-gsa]

LGTM! Do the parentheses and dashes automatically appear when the user types a numeric input?

The changes here only affect the initial page load. After page load, it behaves the same as phone inputs behave everywhere else ("add phone", hybrid step), which doesn't auto-format the text in any way, except when switching from one country to another.

Is that something we'd want? Might be worth a ticket to implement.

OK great! I'm cool to leave the phone inputs alone for now except for this improvement on load, since IIRC it currently accepts a variety of user inputted formatting (dashes, no dashes, etc), which is good. Just wanted to check!