feat: support for creating enforcer with model and policy file path

[ramzeng]

No description provided.

[casbin-bot]

@tangyang9464 @JalinWang please review

[CLAassistant]

All committers have signed the CLA.

[ramzeng]

@hsluoyz Please review it, thanks.

[hsluoyz]

No need to add this, it already can be done by: https://casbin.org/docs/model-storage/#load-model-from-code

[ramzeng]

No need to add this, it already can be done by: https://casbin.org/docs/model-storage/#load-model-from-code

m, err := model.NewModelFromString(`
[request_definition]
r = sub, obj, act

[policy_definition]
p = sub, obj, act

[policy_effect]
e = some(where (p.eft == allow))

[matchers]
m = r.sub == p.sub && r.obj == p.obj && r.act == p.act
`)
if err != nil {
    log.Fatalf("error: model: %s", err)
}

// it will return an error, invalid parameters for enforcer
e, err := casbin.NewEnforcer(m, "examples/basic_policy.csv")

when i pass model and policy path,it will return an error.

@hsluoyz