Thread spec doesn't define the order of TLVs in the dataset, so that
we can't call `memcmp` to compare two dataset. If we convert the
dataset to otOperationalDataset and then compare each value of
otOperationalDataset, we will met an issue if the new Thread spec
defines new TLVs in the dataset in the future.
This commit add a new dataset API `otDatasetTlvsCompare` to check
whether two dataset contain the exact same set of TLVs (same types and
values).
This commit adds a method `Dataset::IsSubsetOf()` to check whether one
dataset is a subset of another. A dataset is considered a subset if
all its TLVs, excluding Active/Pending Timestamp and Delay Timer
TLVs, are present in the other dataset with exactly matching values.
This new method simplifies `Dataset::Info::IsSubsetOf()`. The unit
test `test_dataset` is updated to validate the `IsSubsetOf()()`
method.
This commit enhances dataset handling:
- Adds `ValidateTlvs()` which parses and validates all known TLVs
within the `Dataset` and checks for any duplicates.
- Introduces a set of `SetFrom()` methods for constructing a `Dataset`
from various types of inputs, e.g., other `Dataset`, TLV sequences,
`DatasetInfo` structures, bytes read from `Message`. Now they
consistently clear the `Dataset` before setting it.
- Adds `WriteTlvsFrom()` to update a `Dataset` replacing/appending a
set of TLVs.
- Adds `AppendTlvsFrom()` to append an already encoded sequence of
TLVs without validating/checking the format.
- Renames `Get/SetSize()` to `Get/SetLength()` for consistency.
- Adds `test_dataset.cpp` unit test for basic `Dataset` validation.
Zhanglong Xia