Increase minimum Node.js version to 16; recommended to 18

[legobeat]

Explanation

• BREAKING: Drop support for EoL major Node.js versions 14,15,17,19
• Change recommended Node.js version from 14 to 18 LTS
• ci: run on node v20 instead of v19

Unblocks

• deps: Update @metamask/utils to ^8.1.0, ethereum-cryptography to ^2.1.1 #153
  • 6.0.0 #154
    • Update eth-simple-keyring to v6.0.0 KeyringController#264
      • 14.0.0 KeyringController#265
        • deps: Bump @metamask/{eth-json-rpc-provider,rpc-errors}  core#1653
          • deps: Update @metamask/utils and @metamask/rpc-errors  snaps#1728
            • update dependencies in https://github.com/MetaMask/keyring-api/

Blocked by

• 5.1.0 #160
  • deps: @metamask/utils@^5.0.0->^5.0.2 #155
    • Add validateMessage option to signMessage #148
  • deps: @metamask/eth-sig-util@^5.0.2->^6.0.1 #149
• fix(publish): mark scripts as executable #157