'href' should be offered as a completion attribute for 'see'

[sharwell]

This is a follow-up issue for #35667.

See #35667 (comment).

Sample code

/// <summary>
/// <see | />
/// </summary>
private int value;

Expected result

Completion at | should show the href attribute.

Actual result

Completion at | does not include the href attribute.

Additional details

• href should also be added for seealso
• href we need to decide if href should be presented for a