V2 CLI: separate new and init commands

[caiogeraldes]

This is a simple quality of life change I would like to suggest, as it standardizes the CLI of tectonic with that of tools such as cargo or poetry. Not much else to say, tbh.

[pkgw]

Thank you for the submission! This seems like a nice improvement to me. I have two requests:

1. Can you please add a commit fix the clippy error that the CI is flagging? It's unrelated to your change but also should be a trivial fix. (Sometimes when new versions of Rust come out, we start getting new errors without changing our code, because Clippy gets stricter.)
2. Can you please update the documentation as well? The files are in docs/src/v2cli/ and docs/src/SUMMARY.md.

Thanks again!

[caiogeraldes]

The last two commits should hopefully fix the warnings clippy was throwing, most of them concerning the pattern variable_X as type_Y.

However, I could not fix one of them without setting #[allow(clippy::write_literal)] in the following lines:

tests/executable.rs, l.741ff.

        #[allow(clippy::write_literal)]
        writeln!(
            file,
            "{}", // <= works around {} fussiness in Rust format strings
            r#"\newwrite\w
\immediate\openout\w=first.demo\relax
\immediate\write\w{content-un}
\immediate\closeout\w
\immediate\openout\w=second.demo\relax
\immediate\write\w{content-deux}
\immediate\closeout\w
"#

Without it, clippy went into a kind of a loop, asking for more and more curly braces around content-un and content-deux. Considering it is part of a test which is passing, I assumed the warning could be ignored without any issues. I think the issue is with clippy in this case, and I reckon that the comment near "{}", is related.

Edit:
It seems that a new error appeared while building the version for the target x86_64-pc-windows-msvc with vcpkg. I believe it is unrelated to my changes.

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (master@abd98d4). Click here to learn what that means.
The diff coverage is 46.42%.

❗ Current head 92261fa differs from pull request most recent head cf9e093. Consider uploading reports for the commit cf9e093 to get more accurate results

@@            Coverage Diff            @@
##             master     #983   +/-   ##
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  Coverage          ?   45.17%           
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  Files             ?      148           
  Lines             ?    62159           
  Branches          ?        0           
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  Hits              ?    28083           
  Misses            ?    34076           
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Impacted Files	Coverage Δ
crates/xdv/src/lib.rs	0.00% <0.00%> (ø)
src/bin/tectonic/v2cli.rs	46.86% <13.33%> (ø)
crates/bundles/src/cache.rs	79.31% <50.00%> (ø)
crates/bridge_flate/src/lib.rs	33.89% <100.00%> (ø)
src/config.rs	58.97% <100.00%> (ø)
src/docmodel.rs	55.95% <100.00%> (ø)
src/driver.rs	76.17% <100.00%> (ø)
src/io/format_cache.rs	88.23% <100.00%> (ø)
src/test_util.rs	88.00% <100.00%> (ø)

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[pkgw]

Thanks! There's one small thing to fix in the new docs.

As for the Clippy stuff, thanks — when I initially asked there was only one small error, so you ended up doing a lot more work than I wanted to ask of you!

I'll look into the MSVC issue. I think it's something that might not be too hard to fix/work around. I might fix that doc title issue while I'm at it.