Introduced authorization decrease change period parameter to ECDSA

[pdyraga]

Depends on #2960
See threshold-network/solidity-contracts#99

This value protect against malicious operators who manipulate
their weight by overwriting authorization decrease request, and
lowering or increasing their eligible stake this way.

Authorization decrease change period is the time period before the authorization
decrease delay end, during which the authorization decrease request can be
overwritten.

When the request is overwritten, the authorization decrease delay is
reset.

For example, if authorizationDecraseChangePeriod is set to 4
days, authorizationDecreaseDelay is set to 14 days, and someone
requested authorization decrease, it means they can not
request another decrease for the first 10 days. After 10 days pass,
they can request again and overwrite the previous authorization
decrease request. The delay time will reset for them and they
will have to wait another 10 days to alter it and 14 days to
approve it.

If set to a value equal to `authorizationDecreaseDelay, it means
that authorization decrease request can be always overwritten.
If set to zero, it means authorization decrease request can not
be overwritten until the delay end, and one needs to wait for the entire
authorization decrease delay to approve their decrease or to alter it.

(1) authorization decrease requested timestamp
(2) from this moment authorization decrease request can be
    overwritten
(3) from this moment authorization decrease request can be
    approved, assuming it was NOT overwritten in (2)

  (1)                            (2)                        (3)
 --x------------------------------x--------------------------x---->
   |                               \________________________/
   |                             authorizationDecreaseChangePeriod
    \______________________________________________________/
                   authorizationDecreaseDelay

[pdyraga]

#2960 got merged so I rebased this one over main and marked it as ready for review @nkuba

[nkuba]

The same comments I left in #2960 apply here. Non-blocking so merging it and please handle both in one follow-up.