feat: z-index and opacity for ui elements

[AlejandroAlvarezMelucciDCL]

Addresses the SDK implementation for issue decentraland/unity-explorer#4088

Related PRs:
Protocol: decentraland/protocol#274
E@: decentraland/unity-explorer#4366

[github-actions]

Test this pull request

• The @dcl/sdk package can be tested in scenes by running

  npm install "https://sdk-team-cdn.decentraland.org/@dcl/js-sdk-toolchain/branch/feat/z-index-and-opacity-for-uielements/dcl-sdk-7.8.10-15570365802.commit-f58492e.tgz"

• To test with npx init

  export SDK_COMMANDS="https://sdk-team-cdn.decentraland.org/@dcl/js-sdk-toolchain/branch/feat/z-index-and-opacity-for-uielements/dcl-sdk-commands-7.8.10-15570365802.commit-f58492e.tgz"
  npx $SDK_COMMANDS init

• The @dcl/inspector package can be tested by visiting this url

  • Or by installing it via NPM

  npm install "https://sdk-team-cdn.decentraland.org/@dcl/js-sdk-toolchain/branch/feat/z-index-and-opacity-for-uielements/@dcl/inspector/dcl-inspector-7.8.10-15570365802.commit-f58492e.tgz"

• The /changerealm command to test test in-world

  /changerealm https://sdk-team-cdn.decentraland.org/ipfs/feat/z-index-and-opacity-for-uielements-e2e
  

• You can preview this build entering:
  https://playground.decentraland.org/?sdk-branch=feat/z-index-and-opacity-for-uielements