Invalid multi-byte sequences cause internal file translations (to UTF8) to fail

[Colengms]

Opening this to track an issue I noticed while investigating: #13078

If files.encoding is set to a multi-byte encoding, and an invalid multi-byte sequence is detected, the translation would fail. This should instead skip the invalid sequece and continue trying to translate the encoding.

[v-frankwang]

@Colengms @sean-mcmanus We went to verify the issue in the latest C++ extension 1.24.1 (pre-release) according to the following steps, is the gif showing the expected result?
If our validation steps are not correct, could you share our detailed validation steps?

Verification Steps:

1. Create a Demo folder in PC.
2. Open Demo with VSCode, then add a .cpp file and paste the following code:

#include <iostream>
 
int main() {
    
    const char* invalidSequence = "\xC3\x28"; // Invalid UTF-8 sequence
    std::cout << "Invalid sequence: " << invalidSequence << std::endl;
    return 0;
}

3. Navigate to the bottom toolbar and select the GB18030 encode.
4. Run the .cpp file.

Verification Results: Skip invalid sequece and run the file successfully