Add Storage Region Validation

[RoseSecurity]

What and Why

• Formatting update
• Adds storage_region validation for available regions obtained via:

package main

import (
    "context"
    "fmt"
    "os"
    openapiclient "github.com/cloudsmith-io/cloudsmith-api-go"
)

func main() {

    configuration := openapiclient.NewConfiguration()
    apiClient := openapiclient.NewAPIClient(configuration)
    resp, r, err := apiClient.StorageRegionsApi.StorageRegionsList(context.Background()).Execute()
    if err != nil {
        fmt.Fprintf(os.Stderr, "Error when calling `StorageRegionsApi.StorageRegionsList``: %v\n", err)
        fmt.Fprintf(os.Stderr, "Full HTTP response: %v\n", r)
    }
    // response from `StorageRegionsList`: []StorageRegion
    fmt.Fprintf(os.Stdout, "Response from `StorageRegionsApi.StorageRegionsList`: %v\n", resp)
}

Output:

Response from `StorageRegionsApi.StorageRegionsList`: [{Default Region default} {Northern California, United States us-norcal} {Sydney, Australia au-sydney} {Singapore sg-singapore} {Montreal, Canada ca-montreal} {Frankfurt, Germany de-frankfurt} {Oregon, United States us-oregon} {Ohio, United States us-ohio} {Dublin, Ireland ie-dublin}]

Adds validation using:

"storage_region": {
Type: schema.TypeString,
Description: "The Cloudsmith region in which package files are stored." +
	"Supported regions include: Northern California, United States (us-norcal), Sydney, Australia (au-sydney)," +
	"Singapore (sg-singapore), Montreal, Canada (ca-montreal), Frankfurt, Germany (de-frankfurt), Oregon," +
	"United States (us-oregon), Ohio, United States (us-ohio), Dublin, Ireland (ie-dublin)",
Optional:     true,
Computed:     true,
ForceNew:     true,
ValidateFunc: validation.StringInSlice([]string{"us-norcal", "au-sydney", "sg-singapore", "ca-montreal", "de-frankfurt", "us-oregon", "us-ohio", "ie-dublin"}, false),
},

[BartoszBlizniak]

Thank you for your contribution! Unfortunately forked PR's won't work with our acceptance testing therefore, I have to create an internal branch and merge those in, your contribution has been noted and it will be part of Pull 107!