bug(developer): 0-th elem needs zero offset 🙀

[srl295]

https://github.com/keymanapp/keyman/blob/feature-ldml/core/src/ldml/C7043_ldml.md#c704323-elemtransform-and-reorder-element-strings says about elem

The first entry in the element string list MUST be the null element string, which has zero length and zero offset.

but on inspection, the first (0th) element string list has a zero length, but repeats the offset of the second (1st) entry.

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for #7042 found during #7234

[mcdurdin]

See also https://github.com/keymanapp/keyman/pull/7437/files#diff-95985cb44c34779804524113d19f84c84c0df3809790667a95bd3592e3a9e7cbR307