PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/nestjs/nest/blob/master/CONTRIBUTING.md
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes

What is the new behavior?

This PR introduce EthersSigner as Injectable Service, which can be used to sign messages and transactions and send signed transactions to the Ethereum Network to execute state changing operations.

Does this PR introduce a breaking change?

• Yes
• No

The option providerName is not longer necessary in forRoot and forRootAsync functions.