lfs: improve the hints for common errors in the Batch API The previous message was too debug-ish and less action oriented than a hint should be. The remaining errors that aren't handled are more along the lines of programming errors (not using POST, bad accept type, etc), so I'm not bothering with that. The friendly errors purposely use `self.baseurl` instead of the full Batch API endpoint because I'd expect some copy/paste/modify on the part of the user here, and it would be more confusing if '/objects/batch' magically appeared, but shouldn't be used in the config setting. It still seems like the right thing for debugging in the catchall case.

lfs: provide more Batch API error info via a hint in the raised exception A coworker had a typo in `lfs.url`, forgot it was even set because usually the blob server is inferred, and then got a 404. It would have been easier to debug with the failing URL printed.

scmutil: display the optional hint when handling StorageError in catchall() Other than CensoredNodeError (which is also a StorageError), it looks like all exceptions with a hint display them. I'm not sure that it makes sense to have a hint for censored nodes, so I'm not bothering with that. It looks like nobody is using this yet, as the tests don't change.

sparse-revlog: align endrevidx usages in the _slicechunktosize All "startrevidx..endrevidx" ranges in this function are now half-open.

sparse-revlog: use `span` variable as intended The variable was planned to be used in the while condition but was not used yet.

tests: stabilize test-commandserver.t on Windows It looks like new test coverage in 054d0fcba2c4, rather than a code change.

histedit: conditionalize the imports of 'fcntl' and 'termios' The recent import of chistedit in c36175456350 made Windows sad. I'm not sure if there's other stuff that needs to be done here (e.g. change the default interface), but this makes the tests run again. It would have been nicer if the error message indicated these modules were the problem, but instead it said "*** failed to import extension histedit: No module named histedit". I'm not sure if there's anything we can do about that.

logtoprocess: update commandfinish options arguments d2c997b8001f changed the logtoprocess API with the effect of not exposing the positional arguments to the logtoprocess scripts anymore. We have some scripts that use the duration and return code of the "commandfinish" event to monitor hg calls. Update the logging of the "commandfinish" to expose those values as options argument, which will be accessible as `OPT_RETURN_CODE` and `OPT_DURATION` in logtoprocess arguments. The code has been formatted with Black. Differential Revision: https://phab.mercurial-scm.org/D5282