Feat: Schema Validation Overhaul (#128)

## What

* Overhaul schema validation by adding `internal/schemautils` and
package
* Overhaul general utils pattern by removing `utils.go` adding
`internal/datautils.go`
* Rename and move `client` package to `codefresh.cfclient`
* Ensure plan-time CRON validation for `codefresh_pipeline` matches
current API constraints, while maintaining backwards compatibility for
the deprecated `codefresh_pipeline_cron_trigger` resource, which has
different API constraints (6 fields instead of 5)

## Why

* More DRY
* Better package structure
* CRON Validation fix

## Notes
<!-- Add any notes here -->

## Checklist

* [x] _I have read
[CONTRIBUTING.md](https://github.com/codefresh-io/terraform-provider-codefresh/blob/master/CONTRIBUTING.md)._
* [x] _I have [allowed changes to my fork to be
made](https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/working-with-forks/allowing-changes-to-a-pull-request-branch-created-from-a-fork)._
* [x] _I have added tests, assuming new tests are warranted_.
* [x] _I understand that the `/test` comment will be ignored by the CI
trigger [unless it is made by a repo admin or
collaborator](https://codefresh.io/docs/docs/pipelines/triggers/git-triggers/#support-for-building-pull-requests-from-forks)._

Author: korenyoni

client/account.go renamed to codefresh/cfclient/account.go

@@ -1,4 +1,4 @@
-package client
+package cfclient
 
 import (
 	"errors"

client/api_key.go renamed to codefresh/cfclient/api_key.go

@@ -1,10 +1,11 @@
-package client
+package cfclient
 
 import (
 	"errors"
 	"fmt"
-	"github.com/hashicorp/terraform-plugin-sdk/v2/helper/acctest"
 	"log"
+
+	"github.com/hashicorp/terraform-plugin-sdk/v2/helper/acctest"
 )
 
 type ApiKeySubject struct {

client/client.go renamed to codefresh/cfclient/client.go

@@ -1,4 +1,4 @@
-package client
+package cfclient
 
 import (
 	"bytes"

client/context.go renamed to codefresh/cfclient/context.go

@@ -1,4 +1,4 @@
-package client
+package cfclient
 
 import (
 	"fmt"

client/current_account.go renamed to codefresh/cfclient/current_account.go

@@ -1,4 +1,4 @@
-package client
+package cfclient
 
 import (
 	"encoding/json"

client/gitops_abac_rules.go renamed to codefresh/cfclient/gitops_abac_rules.go

@@ -1,4 +1,4 @@
-package client
+package cfclient
 
 import (
 	"fmt"

client/gql_client.go renamed to codefresh/cfclient/gql_client.go

@@ -1,4 +1,4 @@
-package client
+package cfclient
 
 import (
 	"bytes"

client/hermes_trigger.go renamed to codefresh/cfclient/hermes_trigger.go

@@ -1,4 +1,4 @@
-package client
+package cfclient
 
 import (
 	"fmt"

client/hermes_trigger_event.go renamed to codefresh/cfclient/hermes_trigger_event.go

@@ -1,4 +1,4 @@
-package client
+package cfclient
 
 import (
 	"fmt"

client/idp.go renamed to codefresh/cfclient/idp.go

@@ -1,4 +1,4 @@
-package client
+package cfclient
 
 import (
 	"errors"