## Issue being fixed or feature implemented
HD wallets are old-existsing feature, appeared in Dash years ago, but
enabling HD wallets is not trivial task that requires multiple steps and
command line/rpc calls.
Let's have them enabled by default.
## What was done?
- HD wallets are enabled by default. Currently behavior `dashd`,
`dash-qt` are similar to run with option `-usehd=1`
- the rpc `upgradewallet` do not let to upgrade from non-HD wallet to HD
wallet to don't encourage user use non-crypted wallets (postponed till
v21)
- the initialization of ScriptPubKey is updated to be sure that encypted
HD seed is never written on disk (if passphrase is provided)
- enabled and dashified a script `wallet_upgradewallet.py` which test
compatibility between different versions of wallet
## What is not done?
- wallet tool still does not support passhprase, HD seed can appear on
disk
- there's no dialog that show user a mnemonic phrase and encourage him
to make a paper backup
Before removing a command line 'usehd' (backport bitcoin#11250) need to
make at least one major release for fail-over option (if someone wish to
use non-HD wallets only).
## How Has This Been Tested?
Run unit and functional tests.
Enabled new functional test `wallet_upgradewallet.py` that has been
backported long time ago but waited this PR to be enabled.
## Breaking Changes
HD wallets are created by default.
## Checklist:
- [x] I have performed a self-review of my own code
- [x] I have commented my code, particularly in hard-to-understand areas
- [x] I have added or updated relevant unit/integration/functional/e2e
tests
- [ ] I have made corresponding changes to the documentation
- [x] I have assigned this pull request to a milestone
---------
Co-authored-by: UdjinM6 <UdjinM6@users.noreply.github.com>
