feat: added i18n translation to postMessage fields

[bflorian]

Updated the decimal and number settings to support translations of the postMessage field via locale files. Previously translation was not supported. Only literal values could be set with postMessage.

Also fixed a bug in the decimal setting where the i18n key was displayed but not translated, if postMessage was not set.

Types of changes

• [x] Bug fix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)
• [x] I have read the CONTRIBUTING document
• [x] My code follows the code style of this project (hint: install an xo editor plugin)
• [x] Any required documentation has been added
• [ ] I have added tests to cover my changes

[smartthingspi]

:tada: This PR is included in version 4.2.0 :tada:

The release is available on:

• GitHub release
• npm package (@latest dist-tag)

Your semantic-release bot :package::rocket: