Daytona as a library: importable

[afarbos]

Like cloudsql-proxy and many other go binaries, it usually possible to import them within your own go applications. This PR would allow a similar behavior with daytona too, see example below:

package main

import (
	"fmt"
	"log"
	"os"
	"strings"

	cfg "github.com/cruise-automation/daytona/pkg/config"
	"github.com/cruise-automation/daytona/pkg/daytona"
)

func main() {
	os.Setenv("VAULT_SECRETS_FOO_BAR", "secret/foo/bar/")
	config := cfg.DefaultConfig()
	config.AWSAuth = true
	config.SecretEnv = true
	config.VaultAuthRoleName = "awesome-app-vault-role-name"
	if err := daytona.Run(config); err != nil {
		log.Fatalln(err.Error())
	}

	fmt.Println("== env ==")
	for _, e := range os.Environ() {
		pair := strings.SplitN(e, "=", 2)
		fmt.Println(pair[0])
	}
}

A lot of changes are just moving code, there is not actually so much changes more than creating the daytona package.