Proposed changes

This PR includes the implementation of the setRequestManager function to prevent the addition of multiple data listeners.

This bug is caused by calling the setProvider function for each package when an instance is created.
Calling setProvider for each package adds a data listener to each provider internally.

Old Behaviour

1. call setProvider.
2. create RequestManager and register data listener.
3. call setProvider on all children's.
4. create RequestManager and register data listener for each child package.

New Behaviour

1. call setProvider.
2. create RequestManager and register data listener.
3. call setRequestManager on all children's.

Types of changes

Please put an x in the boxes related to your change.

• Bugfix
• New feature or enhancement
• Others

Checklist

Put an x in the boxes that apply. You can also fill these out after creating the PR. If you're unsure about any of them, don't hesitate to ask. We're here to help! This is simply a reminder of what we are going to look for before merging your code.

• I have read the CONTRIBUTING GUIDELINES doc
• I have signed the CLA
• Lint and unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)
• Any dependent changes have been merged and published in downstream modules

Related issues

close #230

Further comments

This PR reflected the changes in web3/web3.js#3156
PR.
The changes in above PR are merged at other PR, but the other PR has many other changes.
So this PR reflected only the changes in web3/web3.js#3156

After this PR is merged, caver-js v1.4.0-rc.1 will be published.