Improve the Byte array binding in the configuration source generator

[tarekgh]

The configuration source generator currently supports binding a byte[] only from Base64-encoded strings. This issue aims to enhance byte array binding to align with the behavior of runtime reflection-based binding. The improvements should include:

• Support for array values in configuration: Enable binding from array-style configuration values (e.g., JSON entries like byteArray: [1, 2, 3, 4]) in addition to Base64 strings.
• Preserve and extend existing arrays: When binding to an already-initialized (non-null) byte array, the configuration values should be appended to the existing array rather than replacing it—consistent with the behavior of other array types.
• Error handling for invalid values: If invalid configuration values are encountered, an exception should be thrown when the BindingOption.ErrorOnUnknownConfiguration flag is enabled.

[dotnet-policy-service]

Tagging subscribers to this area: @dotnet/area-extensions-configuration
See info in area-owners.md if you want to be subscribed.

[tarekgh]

Tests like

runtime/src/libraries/Microsoft.Extensions.Configuration.Binder/tests/Common/ConfigurationBinderTests.cs

Line 2962 in 6da0fa9

Assert.Equal([0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10], instance.ByteArray3);

runtime/src/libraries/Microsoft.Extensions.Configuration.Binder/tests/Common/ConfigurationBinderTests.cs

Line 3002 in 6da0fa9

#if BUILDING_SOURCE_GENERATOR_TESTS

Need to be fixed along with fixing this issue.