Validator dir creation (#1746)

## Issue Addressed

Resolves #1744

## Proposed Changes

- Add `directory::ensure_dir_exists` to the `ValidatorDefinition::open_or_create` method 
- As @pawanjay176 suggested, making the `--validator-dir` non-global so users are forced to include the flag after the `validator` subcommand. Current behavior seems to be ignoring the flag if it comes after something like `validator import`

## Additional Info
N/A

common/account_utils/Cargo.toml

@@ -19,3 +19,4 @@ types = { path = "../../consensus/types" }
 validator_dir = { path = "../validator_dir" }
 regex = "1.3.9"
 rpassword = "5.0.0"
+directory = { path = "../directory" }

common/account_utils/src/validator_definitions.rs

@@ -4,6 +4,7 @@
 //! attempt) to load into the `crate::intialized_validators::InitializedValidators` struct.
 
 use crate::{create_with_600_perms, default_keystore_password_path, ZeroizeString};
+use directory::ensure_dir_exists;
 use eth2_keystore::Keystore;
 use regex::Regex;
 use serde_derive::{Deserialize, Serialize};
@@ -35,6 +36,8 @@ pub enum Error {
     InvalidKeystorePubkey,
     /// The keystore was unable to be opened.
     UnableToOpenKeystore(eth2_keystore::Error),
+    /// The validator directory could not be created.
+    UnableToCreateValidatorDir(PathBuf),
 }
 
 /// Defines how the validator client should attempt to sign messages for this validator.
@@ -108,6 +111,9 @@ pub struct ValidatorDefinitions(Vec<ValidatorDefinition>);
 impl ValidatorDefinitions {
     /// Open an existing file or create a new, empty one if it does not exist.
     pub fn open_or_create<P: AsRef<Path>>(validators_dir: P) -> Result<Self, Error> {
+        ensure_dir_exists(validators_dir.as_ref()).map_err(|_| {
+            Error::UnableToCreateValidatorDir(PathBuf::from(validators_dir.as_ref()))
+        })?;
         let config_path = validators_dir.as_ref().join(CONFIG_FILENAME);
         if !config_path.exists() {
             let this = Self::default();