Modification of wallet layer classes

[jimni1222]

Proposed changes

This PR introduces modification of caver-wallet

• Removed Wallet class and moved KeyringContainer to packages/caver-wallet/index.js (The code didn't change except signWithKey, signWithKeys, signFeePayerWithKey and signFeePayerWithKeys)

• Chagned signing function(signWithKey, signWithKeys, signFeePayerWithKey and signFeePayerWithKeys) in KeyringContainer to use signing function in Transaction (no more duplicated logic for signging)

• Changed caver.wallet.generate return type from void to Array<string>

• Fixed scrypt-shim CI bug. (refer web3@1.2.3 has broken dependencies web3/web3.js#3210 and Fix npm installation error for websocket and scrypt-shim web3/web3.js#3211)

• Implemented below functions in Keyring

  • generateSingleKey
  • generateMultipleKeys
  • generateRoleBasedKeys

After this PR caver-js v1.5.0-rc.1 will be released.

Types of changes

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• Bugfix
• New feature or enhancement
• Others

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• I have added tests that prove my fix is effective or that my feature works
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• Any dependent changes have been merged and published in downstream modules

Related issues

refer #249
close #317

Further comments

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