[nearby][framework] Sync DataElement value with spec

Note DataType in DataElement is used for internal implementation only.
We only keep those data element types used for encoding and decoding.
Please use the spec as the only source.

go/nearby-specs-working-doc

Bug: 234155151
Test: -m
Ignore-AOSP-First: nearby_not_in_aosp_yet
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:8182ac22c14e044c5161483a9a96bf594c403e61)
Merged-In: I71754e645742ca4fe20d346763796a1a5e5dae75
Change-Id: I71754e645742ca4fe20d346763796a1a5e5dae75