[tugger-wix] Adding EULA rtf does not work

[LehMaxence]

The WixVariable ID to add the EULA rtf has a typo, it should be WixUILicenseRtf and not WixUILicenseRTF`

This results in having the default lorem ipsum text in the license dialog box instead of the actual rtf text.

Typo:

https://github.com/indygreg/PyOxidizer/blob/b78b0cb75f4317c45408bbc9a569c062c482c679/tugger-wix/src/simple_msi_builder.rs#L521

Reference:

https://wixtoolset.org/docs/v3/wixui/wixui_customizations/#specifying-a-license-file

[6xzo]

I ran into a similar issue with a typo in the id for the ui banner bitmap image, and pushed a fix. (I checked and the dialog image was already OK.)