Address API review feedback

"Can the getters be made public so this can be CTS tested?"
"Please add getters and mark them @TestApi so CTS can use them."
"Antispoofkey and AntiSpoofkey should be AntispoofKey."
"please rename accountKey to something like deviceAccountKey"

Getters are added as SystemApi since @TestApi doesn't work well with mainline.

BUG: 218682005
BUG: 222489854
Test: unit test
Ignore-AOSP-First: nearby_not_in_aosp_yet
CTS-Coverage-Bug: 205591293
Change-Id: I9e1a69b2b744b0f19fa13fe6215237317725390d
1 file changed