debugcommands: ability to suppress logging of handshake The tests for calling wire protocol commands were getting quite verbose because they included the results of the capabilities request. Furthermore, it was annoying to have to update several tests every time the capabilities response changed. The only tests that really care about the low-level details of the capabilities requests are those testing the protocol handshake. And those are mostly not instantiating peer instances or are contained to limited files. This commit adds an option to `hg debugwireproto` to suppress logging of the handshake. The shell helper function to perform HTTP tests has been updated to use this by default. Lots of excessive test output has gone away. Differential Revision: https://phab.mercurial-scm.org/D3378