Move swtpm_localca sources from samples/ to src/

Move swtpm_localca sources from samples/ to src/

- Move swtpm_localca's sources out of samples/ (where they no longer
  belong now that swtpm_localca is a binary) to src/swtpm_localca/.
- Tests now call the swtpm_localca binary directly at the location
  where it was built, as they do with all other compiled programs.
- Simplify samples/swtpm-localca.in and delete swtpm-localca.2inst,
  removing the now-unnecessary logic to selectively call swtpm_localca
  from different locations (samples/ when running tests vs. /usr/bin/
  post-installation).

Signed-off-by: Nick Chevsky <nchevsky@users.noreply.github.com>