chore: offer to install copier

[alexeagle]

Refactors to use the post_scaffold hook to generate the requirements.txt files, because it's too difficult to keep their content known ahead-of-time and prevents conditionals in the pyproject.toml for which packages should be installed.
We want to be responsive to prompts and be able to install packages if requested.

Also run buildifier in the post_scaffold hook, now we don't have to treat the whitespace in the template with incredible care :)

Note, the post_scaffold hook feature was introduced in v0.1.0 of the scaffold tool in hay-kot/scaffold#167 so we have to drop support for older versions now.

[thesayyn]

Also run buildifier in the post_scaffold hook, now we don't have to treat the whitespace in the template with incredible care :)

I like this

[thesayyn]

I briefly mentioned to @jbedard about how it is confusing to know which order to invoke go mod tidy bazel mod tidy and all other package manager related functions.

Would be great to have a feature in aspect-cli that does it for you automatically, like bazel configure lock which tracks package manager files and prompts to run a command similar to Android Studio Gradle Sync Now button.

[alexeagle]

Yeah that's what repin.sh is trying to hint at here. It should include Go also.