Bump rc0->rc1. Cannott re-upload pip package with the same RC

PiperOrigin-RevId: 200846594

1. Rearrange linesearch package and build rules to ensure inclusion i…

…n pip pkg

build. 2. Rename hz_line_search to eliminate abbreviation, and omit
'_line_search' since it'll now be scoped to the linesearch sub-package

PiperOrigin-RevId: 200793549