templater: extract function scanning template string This provides a tokenizer-level view of template fragments, and will be used to substitute patterns in outermost 'string' tokens.

tests: expand test coverage for updating phases Consolidating the tests demonstrated that there are behavior differences when pushing phases between bundle1 and bundle2. A reason for this is the behavior of legacy pushes where the client queries the state of phases and then conditionally updates phases after an "unbundle" is processed. This behavior is expected. The tests were incomplete because they only tested the case of a publishing repo. In this commit, we add a variant for a non-publishing repo. We still see some differences between the legacy and bundle2 exchanges. But they are less pronounced. The behavior of not firing a pushkey hook when phases are updated as part of changegroup application feels weird to me. I'm not sure if this is a feature or a bug. By the time the "pushkey" or "phases" bundle2 part is applied, the phases have already been moved on a publishing repository. We fire the "pushkey" hook regardless, even though it would be a no-op. This is the part that feels the most buggy.

tests: consolidate test-push-http.t and test-push-http-bundle1.t These tests were initially copies of each other. Now that we have #testcases support in .t tests, we can consolidate them. The changes to test-push-http.t reflect the differences between that file and test-push-http-bundle1.t. The variances in phases push behavior are the biggest differences. The test will be updated in a subsequent commit to make the differences more clear and to expand test coverage. For now, let's just port the differences verbatim to get the tests consolidated.