Implement test-only for python_ rules

Similar to: aosp/3040036 and aosp/3035329, implements a test-only
property for python_library and sets it for python_host.

This combined with aosp/3045317 produces:
	gqui from  "flatten(~/aosp-main-with-phones/out/soong/ownership/all_teams.pb, teams)" proto ~/aosp-main-with-phones/build/soong/android/team_proto/team.proto:AllTeams 'select teams.kind, count(*) total, sum(teams.test_only) as test_only, sum(teams.top_level_target) as top_level, where teams.kind like "%py%"  group by teams.kind'
	+-----------------------------+-------+-----------+-----------+
	|         teams.kind          | total | test_only | top_level |
	+-----------------------------+-------+-----------+-----------+
	| cpython3_cc_defaults        |     1 |         0 |         0 |
	| cpython3_cc_prebuilt_binary |     4 |         0 |         0 |
	| python_binary_host          |   222 |         0 |         0 |
	| python_defaults             |    27 |         0 |         0 |
	| python_library              |    38 |         0 |         0 |
	| python_library_host         |   131 |         0 |         0 |
	| python_test                 |     5 |         5 |         5 |
	| python_test_host            |   172 |       172 |       172 |
	+-----------------------------+-------+-----------+-----------+

Change-Id: Iea14fcdbfd782d37ac0a3c780820deeed5f1923d
Test: m blueprint_tests
Test: go test ./python

0 files changed, 0 insertions, 0 deletions