Make rolling session more resilient in case of long finality stalls (#6106)

* Impl dynamic window size. Keep sessions for unfinalized chain

Signed-off-by: Andrei Sandu <andrei-mihail@parity.io>

* feedback

Signed-off-by: Andrei Sandu <andrei-mihail@parity.io>

* Stretch also in contructor plus  tests

Signed-off-by: Andrei Sandu <andrei-mihail@parity.io>

* review feedback

Signed-off-by: Andrei Sandu <andrei-mihail@parity.io>

* fix approval-voting tests

Signed-off-by: Andrei Sandu <andrei-mihail@parity.io>

* grunting: dispute coordinator tests

Signed-off-by: Andrei Sandu <andrei-mihail@parity.io>

* add session window column

Signed-off-by: Andrei Sandu <andrei-mihail@parity.io>

* integrate approval vote and fix tests

Signed-off-by: Andrei Sandu <andrei-mihail@parity.io>

* fix rolling session tests

Signed-off-by: Andrei Sandu <andrei-mihail@parity.io>

* Small refactor

Signed-off-by: Andrei Sandu <andrei-mihail@parity.io>

* WIP, tests failing

Signed-off-by: Andrei Sandu <andrei-mihail@parity.io>

* Fix approval voting tests

Signed-off-by: Andrei Sandu <andrei-mihail@parity.io>

* fix dispute-coordinator tests

Signed-off-by: Andrei Sandu <andrei-mihail@parity.io>

* remove uneeded param

Signed-off-by: Andrei Sandu <andrei-mihail@parity.io>

* fmt

Signed-off-by: Andrei Sandu <andrei-mihail@parity.io>

* fix loose ends

Signed-off-by: Andrei Sandu <andrei-mihail@parity.io>

* allow failure and tests for it

Signed-off-by: Andrei Sandu <andrei-mihail@parity.io>

* fix comment

Signed-off-by: Andrei Sandu <andrei-mihail@parity.io>

* comment fix

Signed-off-by: Andrei Sandu <andrei-mihail@parity.io>

* style fix

Signed-off-by: Andrei Sandu <andrei-mihail@parity.io>

* new col doesn't need to be ordered

Signed-off-by: Andrei Sandu <andrei-mihail@parity.io>

* fmt and spellcheck

Signed-off-by: Andrei Sandu <andrei-mihail@parity.io>

* db persist tests

Signed-off-by: Andrei Sandu <andrei-mihail@parity.io>

* Add v2 config and cols

Signed-off-by: Andrei Sandu <andrei-mihail@parity.io>

* DB upgrade WIP

Signed-off-by: Andrei Sandu <andrei-mihail@parity.io>

* Fix comments

Signed-off-by: Andrei Sandu <andrei-mihail@parity.io>

* add todo

Signed-off-by: Andrei Sandu <andrei-mihail@parity.io>

* update to parity-db to "0.4.2"

Signed-off-by: Andrei Sandu <andrei-mihail@parity.io>

* migration complete

Signed-off-by: Andrei Sandu <andrei-mihail@parity.io>

* One session window size

Signed-off-by: Andrei Sandu <andrei-mihail@parity.io>

* fix merge damage

Signed-off-by: Andrei Sandu <andrei-mihail@parity.io>

* fix build errors

Signed-off-by: Andrei Sandu <andrei-mihail@parity.io>

* fmt

Signed-off-by: Andrei Sandu <andrei-mihail@parity.io>

* comment fix

Signed-off-by: Andrei Sandu <andrei-mihail@parity.io>

* fix build

Signed-off-by: Andrei Sandu <andrei-mihail@parity.io>

* make error more explicit

Signed-off-by: Andrei Sandu <andrei-mihail@parity.io>

* add comment

Signed-off-by: Andrei Sandu <andrei-mihail@parity.io>

* refactor conflict merge

Signed-off-by: Andrei Sandu <andrei-mihail@parity.io>

* rename col_data

Signed-off-by: Andrei Sandu <andrei-mihail@parity.io>

* add doc comment

Signed-off-by: Andrei Sandu <andrei-mihail@parity.io>

* fix build

Signed-off-by: Andrei Sandu <andrei-mihail@parity.io>

* migration: move all cols to v2

Signed-off-by: Andrei Sandu <andrei-mihail@parity.io>

Signed-off-by: Andrei Sandu <andrei-mihail@parity.io>