fix: place the config file in XDG_CONFIG_HOME instead of HOME

[rkpattnaik780]

Description

Place the config file in $XDG_CONFIG_HOME if it exists, otherwise place it in $HOME/.config.

Fixes #442

Verification Steps

1. Login by running the command go run ./cmd/rhoas login.
2. Run echo $XDG_HOME_CONFIG.
3. If you get a path, run nano $XDG_HOME_CONFIG/.rhoascli.json, you should be able to see the config file.
4. If echo $XDG_HOME_CONFIG returns empty string, running nano $HOME/.config/.rhoascli.json should open the config file.

Type of change

• Bug fix (non-breaking change which fixes an issue)

Checklist

• Documentation added for the feature
• CI and all relevant tests are passing
• Code Review completed
• Verified independently by reviewer

[wtrocki]

I'm not big fan of using small utility packages with go, however this works and does the job so it looks like we can merge it

Will leave to our team lead to approve tommorow

[rkpattnaik780]

The package was mentioned here.
Alternatively we could make some changes to the package's UserConfig method:

func (d *dirs) UserConfig() string {
	baseDir := os.Getenv("XDG_CONFIG_HOME")
	if baseDir == "" {
		baseDir = filepath.Join(os.Getenv("HOME"), ".config")
	}

	return filepath.Join(baseDir, d.name)
}

[wtrocki]

Verified all good to merge