packaging: extract py2exe functionality to own module py2exe builds are shared between Inno Setup and WIX. We'll want the logic for performing py2exe builds to be reusable across the code for both installers. This commit extracts the py2exe-specific functionality into its own module. There's definitely room to customize things further. This will be done in future commits, as necessary. (I'm not even sure what customizations WIX will require yet. Presumably a lot.) Differential Revision: https://phab.mercurial-scm.org/D6091

packaging: extract python exe info to own function This is generic functionality. We'll need it for WIX. As part of the port, we expose the full version and return the data as a dict. Differential Revision: https://phab.mercurial-scm.org/D6090

packaging: don't use temporary directory We were no longer doing anything with it after extracting virtualenv and py2exe to the build directory. Differential Revision: https://phab.mercurial-scm.org/D6089

packaging: extract virtualenv and py2exe to build directory The build directory is essentially a cache. We can extract the virtualenv and py2exe package sources to this directory. Differential Revision: https://phab.mercurial-scm.org/D6088

packaging: move Inno Setup core logic into a module Aspects of building the Inno Setup and WIX installers are shared. It will make sense for them to share code. Plus, having code in a reusable library (as opposed to a standalone script) is just a better approach. This commit moves the core logic to build the Inno Setup installer into the hgpackaging package. inno/build.py is now a simple frontend script that calls into a module to do the bulk of the work. As part of this change, I also found a typo in build() where it was referencing "iscc" instead of "iscc_exe." Because "iscc" was in the global scope via the only caller, things just happened to work before. Another benefit of always using functions and not putting global code for __main__ in the same file as library code. Differential Revision: https://phab.mercurial-scm.org/D6087

packaging: move find_vc_runtime_files() into hgpackaging.util In preparation for moving the bulk of the Inno Setup code into hgpackaging. Differential Revision: https://phab.mercurial-scm.org/D6086

packaging: move DOWNLOADS dict to hgpackaging.downloads We'll want to keep state in sync between multiple packaging tools. It makes sense to share a central data structure defining downloads. We also change the function to return the downloads entry so callers don't have to access the global DOWNLOADS in the new location. Differential Revision: https://phab.mercurial-scm.org/D6085

packaging: split downloading code into own module As we will introduce more code to support packaging, it will be useful to have download code in its own module. Differential Revision: https://phab.mercurial-scm.org/D6084