This commit introduces the `OffsetRange` class, which represents a
range of offsets within a `Message` or data buffer (i.e., a starting
offset and a length indicating the number of bytes in the range).
The class provides methods for common operations:
- Getting the start or end offset, or the remaining length.
- Checking if the range is empty or contains a certain number of
bytes.
- Advancing the start offset by a given amount, ensuring it never goes
beyond the end offset.
- Shrinking the range's length.
The new `OffsetRange` class simplifies methods that previously used
separate `aOffset` and `aLength` input parameters, improving code
readability and maintainability. It also facilitates reading and
processing content within a specified range.
For example, `Tlv::FindTlvValueOffsetRange()` now directly returns an
`OffsetRange` indicating the location of the TLV value. The `Message`
class is also updated with new `Read()` and `Append()` method variants
that accept `OffsetRange` arguments. These methods ensure that read
content is contained within the specified `OffsetRange`.
Abtin Keshavarzian