Cw 657 new buy sell flow (#1553)

* init commit

* onramper

* moonPay

* dfx provider

* meld

* dfx payment methods

* fiat buy credentials

* moonpay payment method

* payment loading state

* dfx sell quote

* onramper launch trade

* meld launch trade

* country picker

* update option tile

* buy/sell action

* meld refactor

* update pr_test_build.yml

* ui fixes

* revert country picker commit

* update the ui

* recommended providers

* payment method [skip ci]

* provider option tile

* remove buy action

* minor fixes

* update the best rate when the amount is changed

* fixes for currency title

* fix icons

* code refactoring

* null issue

* code review fixes

* Update pr_test_build_linux.yml

* Update meld_buy_provider.dart

* Update meld_buy_provider.dart

* add show wallets action

* remove default sell / buy provider setting

* localisation

* providerTypes

* icons

* remove duplicate file [skip ci]

* minor changes [skip ci]

* fixes from review

* disable dfx for non eur/chf currencies
fix providers to be fetched with the selected currency

* fix breaking from loop if one element failed

* fix minor naming issue from merging conflicts

* add fiat check for moonpay

* fix address validation

* merge conflict

* fix destination and source currency

* minor fix

* minor fix

* update the flow

* fix bch address format

* fix wallet addresses

* fix initial fetching amount.

* Update address_validator.dart

* review comments

* revert switch case to return null

* minor fix

---------

Co-authored-by: OmarHatem <omarh.ismail1@gmail.com>

lib/src/screens/settings/other_settings_page.dart

@@ -57,22 +57,6 @@ class OtherSettingsPage extends BasePage {
                   handler: (BuildContext context) =>
                       Navigator.of(context).pushNamed(Routes.changeRep),
                 ),
-              if(_otherSettingsViewModel.isEnabledBuyAction)
-              SettingsPickerCell(
-                title: S.current.default_buy_provider,
-                items: _otherSettingsViewModel.availableBuyProvidersTypes,
-                displayItem: _otherSettingsViewModel.getBuyProviderType,
-                selectedItem: _otherSettingsViewModel.buyProviderType,
-                onItemSelected: _otherSettingsViewModel.onBuyProviderTypeSelected
-              ),
-              if(_otherSettingsViewModel.isEnabledSellAction)
-              SettingsPickerCell(
-                title: S.current.default_sell_provider,
-                items: _otherSettingsViewModel.availableSellProvidersTypes,
-                displayItem: _otherSettingsViewModel.getSellProviderType,
-                selectedItem: _otherSettingsViewModel.sellProviderType,
-                onItemSelected: _otherSettingsViewModel.onSellProviderTypeSelected,
-              ),
               SettingsCellWithArrow(
                 title: S.current.settings_terms_and_conditions,
                 handler: (BuildContext context) =>