switch tool tests to build runner

[jonahwilliams]

Description

Switch tool tests to use build_runner. The test execution should be noticeably faster, with the trade-off of doing compilation up front. The compilation artifacts can be shared across shards though, which should allow us to increase overall test throughput.

shard	pub test	build_runner test
tool_tests-linux	30 min	24 min
tool_tests-windows	35 min	32 min
tool_tests-macos	30 min	25 min

Related Issues

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[dnfield]

LGTM