`cliui`: use pointers for `spinner` object to prevent printing inconsistencies

Referring to this message: https://github.com/ignite/cli/pull/2920#issuecomment-1279345112

Use pointers to solve the underlined issues.

Currently if a `session` is initializes without `cliui.StartSpinner()`
```
session := cliui.New()
```
there are printing inconsistencies as the spinner will be `nil` in the high-level method
