Given an integer array `data` representing the data, return whether it is a valid UTF-8 encoding.

A character in UTF8 can be from 1 to 4 bytes long, subjected to the following rules:

1. For a 1-byte character, the first bit is a `0`, followed by its Unicode code.
2. For an n-bytes character, the first `n` bits are all one's, the `n + 1` bit is `0`, followed by `n - 1` bytes with the most significant `2` bits being `10`.

This is how the UTF-8 encoding would work:

       Char. number range  |        UTF-8 octet sequence
          (hexadecimal)    |              (binary)
       --------------------+---------------------------------------------
       0000 0000-0000 007F | 0xxxxxxx
       0000 0080-0000 07FF | 110xxxxx 10xxxxxx
       0000 0800-0000 FFFF | 1110xxxx 10xxxxxx 10xxxxxx
       0001 0000-0010 FFFF | 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx

Note: The input is an array of integers. Only the least significant 8 bits of each integer is used to store the data. This means each integer represents only 1 byte of data.

Example 1:

    Input: data = [197,130,1]
    Output: true
    Explanation: data represents the octet sequence: 11000101 10000010 00000001.
    It is a valid utf-8 encoding for a 2-bytes character followed by a 1-byte character.

Example 2:

    Input: data = [235,140,4]
    Output: false
    Explanation: data represented the octet sequence: 11101011 10001100 00000100.
    The first 3 bits are all one's and the 4th bit is 0 means it is a 3-bytes character.
    The next byte is a continuation byte which starts with 10 and that's correct.
    But the second continuation byte does not start with 10, so it is invalid.

Constraints:

- `1 <= data.length <= 2 * 104`
- `0 <= data[i] <= 255`