[BUG] AzureCliCredential improperly parses expiresOn returned from 'az account get-access-token'

[schaabs]

The the value of the "expiresOn" feild returned from az account get-access-token is a local time with no timezone information, for example "2020-10-07 09:53:24.773201". However, when we parse we use the AdjustToUniversal date time style

azure-sdk-for-net/sdk/identity/Azure.Identity/src/AzureCliCredential.cs

Line 174 in db3c89b

: DateTimeOffset.ParseExact(root.GetProperty("expiresOn").GetString(), "yyyy-MM-dd HH:mm:ss.ffffff", CultureInfo.InvariantCulture, DateTimeStyles.AdjustToUniversal);

According to the documentation AdjustToUniversal will result in a DateTimeOffset with Kind == Unspecified if no timezone is included in the string unless the AssumeLocal flag is also specified, so it can be adjusted to UTC.

Date and time are returned as a Coordinated Universal Time (UTC). If the input string denotes a local time, through a time zone specifier or AssumeLocal, the date and time are converted from the local time to UTC. If the input string denotes a UTC time, through a time zone specifier or AssumeUniversal, no conversion occurs. If the input string does not denote a local or UTC time, no conversion occurs and the resulting Kind property is Unspecified. This value cannot be used with RoundtripKind.

The code should be updated to pass both flags DateTimeStyles.AdjustToUniversal | DateTimeStyles.AssumeLocal.