fix: check git configuration before exec world create (#74)

Closes: WORLD-1177

## Overview

When user trying to exec `world create` but git configuration `.gitconfig` for username and password is not configured it will be returned error, but the gameshard dir is already created.

The issue is because on the last step of `world create` it will exec git commit, and it will need username and email to be configured in `.gitconfig`

Solutions
Before executing `world create`, world cli will check the git configuration is configured or not. if it's not, world cli will tell the command how to configure the git config.

## Brief Changelog

- Create func for checking git configuration
- Call the function at the first execution of `world create` command

## Testing and Verifying
- Added unit test for checkGitConfig func

common/teacmd/git.go

@@ -32,7 +32,14 @@ type GitCloneFinishMsg struct {
 
 func git(args ...string) (string, error) {
 	var outBuff, errBuff bytes.Buffer
-	_, err := sh.Exec(nil, &outBuff, &errBuff, "git", args...)
+
+	// Define environment variables
+	env := map[string]string{
+		"GIT_COMMITTER_NAME":  "World CLI",
+		"GIT_COMMITTER_EMAIL": "[email protected]",
+	}
+
+	_, err := sh.Exec(env, &outBuff, &errBuff, "git", args...)
 	if err != nil {
 		return "", err
 	}
@@ -94,7 +101,7 @@ func GitCloneCmd(url string, targetDir string, initMsg string) error {
 		return err
 	}
 
-	_, err = git("commit", "-m", initMsg)
+	_, err = git("commit", "--author=\"World CLI <[email protected]>\"", "-m", initMsg)
 	if err != nil {
 		return err
 	}