Added SX1231 UHF Transceiver

Hello, I created the symbol for the SX1231 UHF transceiver.

Datasheet: https://semtech.my.salesforce.com/sfc/p/#E0000000JelG/a/44000000MDkO/lWPNMeJClEs8Zvyu7AlDlKSyZqhYdVpQzFLVfUp.EXs

Associated MRs:

• Footprint: kicad-footprints!3161 (merged)
• FP generator: kicad-footprint-generator!888 (merged)

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Required Settings:

Please configure your personal fork of the KiCad project with the following settings:

1. Settings->General->Visibility->Pipelines should be enabled and set to "Everyone with access".
2. Settings->CI/CD->General Pipelines timeout should be set to >3h .

Configure the merge request as follows:

1. The "Allow commits from members who can merge to the target branch." option check box at the bottom of your merge request must be checked.

• This can later be enabled via the edit button found at the top right (in case you forgot to do it when creating the merge request).

#General Guidelines: All contributions to the kicad library must follow the KiCad library convention

Thanks for creating a pull request to contribute to the KiCad libraries! To speed up integration of your PR, please check the following items:

• Provide a URL to a datasheet for the symbol(s) you are contributing
• An example screenshot image is very helpful
• Ensure that the associated footprints match the official footprint library
  • A new fitting footprint must be submitted if the library does not yet contain one.
• If there are matching footprint PRs, provide link(s) as appropriate
• Check the output of the automated check scripts - fix any errors as required
• Give a reason behind any intentional library convention rule violation.