feat(dashmate): a flag to keep data on reset

[shumkov]

Issue being fixed or feature implemented

We should be able to reset node but keep docker volumes so we don't need to resync Core or Platform again.
This is useful during dashmate upgrade when existing dashmate had outdated docker containers.
Also haveing this you can sync a fullnode and then convert it to masternode.

What was done?

• Added --keep-data flag to keep docker containers to the reset command

How Has This Been Tested?

Locally

Breaking Changes

None

Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have added or updated relevant unit/integration/functional/e2e tests
• I have added "!" to the title and described breaking changes in the corresponding section if my code contains any
• I have made corresponding changes to the documentation if needed

For repository code-owners and collaborators only

• I have assigned this pull request to a milestone

[pshenmic]

we need to update documentation

[shumkov]

I convinced @pshenmic to update the documentation in a separate PR.