Clarify some names in the CreditCardSaveManager::DetectedValue enum

Two of the names in this enum could be misleading:

  - USER_PROVIDED_NAME
  - USER_PROVIDED_EXPIRATION_DATE

The enum tracks what was detected in some form data (past tense), and so
naming the enum values as "USER_PROVIDED" could be read as saying that
the user has already provided this information. However their actual
meaning is that the user still needs to provide this information
(because it is either fully/partially missing and/or cannot be obtained
via the user's Payments profile). To make this clearer, this CL renames
them to:

  - USER_MUST_PROVIDE_NAME
  - USER_MUST_PROVIDE_EXPIRATION_DATE

Bug: None
Change-Id: Ia7fead24ae2fe6e195d87cea3a3fa3e306c05cb3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6967519
Reviewed-by: Olivia Saul <osaul@google.com>
Commit-Queue: Stephen McGruer <smcgruer@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1519982}