Previously, NNS contract required signature of the TLD owner to grant
access for L2 domain name registration. This didn't allow to properly
manage TLDs by committee (only) since it is multi-account and dynamic
while all domains were owned by the single account. Also, such behavior
made it almost impossible to register L2 domains in practice.

To solve the described problems, the following changes are introduced to
the access rules (`register` method of the NNS contract):
 * TLDs are managed only by the committee only;
 * free L2 domains are free-to-take;
 * all L3+ domains are managed by parent domain owner or administrator
   only.

Refs nspcc-dev#334.

Signed-off-by: Leonard Lyubich <leonard@morphbits.io>

In order to register TLD, committee multi-signature must be gathered.
It is not always easy. For example, on "fresh" network, committee
members may not have a notary role, so they will not be able to use
Notary service to collect a signature. At the same time, Notary service
is the only convenient way to collect a multi-signature in a distributed
mode. To simplify the solution of the described task, it would be
convenient to be able to register pre-known TLDs at the NNS contract
deployment stage (which is performed by the committee).

Support list of (name, e-mail) pairs describing pre-defined TLDs as
optional deployment parameters (passed into `_deploy` callback). Also
make `migration.NewContract` to pre-register 'neofs' TLD.

Refs nspcc-dev#334.

Signed-off-by: Leonard Lyubich <leonard@morphbits.io>

Top-level domains aren't NFTs, therefore NNS contract must not treat
them as such. At the same time, technically TLDs are valid domains (e.g.
'org'), so nothing will prevent the user from performing operations with
them. Based on this, the best approach would be treating TLDs as
non-existent domains.

Throw 'token not found' exception on TLD input of any method. The
storage model is left the same: this allows us not to perform migration
and implement the behavior logically.

Refs 334.

Signed-off-by: Leonard Lyubich <leonard@morphbits.io>

Top-level domains are controlled by the committee. Previously, NNS
contract provided `register` method that accepted fixed domain owner.
After recent changes, TLDs were forbidden to be treated as regular
tokens in terms of the NNS contract. According to this, `register`
method is no longer well-suited for TLD registration, so, it's worth to
provide dedicated method for this purpose.

Add `registerTLD` method with signature similar to the `register` one
but w/o owner parameter.

Closes nspcc-dev#334.

Signed-off-by: Leonard Lyubich <leonard@morphbits.io>

Signed-off-by: Leonard Lyubich <leonard@morphbits.io>

After recent changes, some contract methods pre-calculate fragments of
the requested domain name to process TLDs. In most cases, these methods
call `getNameState` function in subsequent instructions which also
performs fragmentation. In order to avoid resource costs for a
duplicated action, an already calculated partition should be reused.

Add `getFragmentedNameState` function which allows to pass
pre-calculated fragments. The function is implemented with the
possibility of a direct call from `getNameState` while maintaining the
behavior of the latter.

Signed-off-by: Leonard Lyubich <leonard@morphbits.io>