Refactor buttons a bit, enable dark mode (#1395)

packages/desktop-client/src/components/FatalError.js

packages/desktop-client/src/components/LoggedInUser.js

packages/desktop-client/src/components/ManageRules.js

packages/desktop-client/src/components/NotesButton.tsx

packages/desktop-client/src/components/Notifications.tsx

packages/desktop-client/src/components/SidebarWithData.js

packages/desktop-client/src/components/ThemeSelector.tsx

packages/desktop-client/src/components/Titlebar.js

packages/desktop-client/src/components/UpdateNotification.js

packages/desktop-client/src/components/accounts/Account.js

...esktop-client/src/components/accounts/AccountSyncCheck.js

packages/desktop-client/src/components/accounts/Balance.js

packages/desktop-client/src/components/accounts/Header.js

...op-client/src/components/accounts/MobileAccountDetails.js

.../desktop-client/src/components/accounts/MobileAccounts.js

packages/desktop-client/src/components/accounts/Reconcile.js

...sktop-client/src/components/autocomplete/Autocomplete.tsx

...p-client/src/components/autocomplete/PayeeAutocomplete.js

...desktop-client/src/components/budget/MobileBudgetTable.js

packages/desktop-client/src/components/budget/misc.js