feat: add a file tracking results from the 1000+ theorems project

[grunweg]

Add a new file 1000.yaml, tracking the formalisation status of theorems
from the 1000+ theorems project. Make check-yaml handle this file also.

Future PRs will

• expose this information on the webpage
• add infrastructure for synchronising this file with the upstream repository
• could add an attribute similar to the stacks attribute, and generate this file from the tagging
• add information on existing formalisation projects in Lean.

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[github-actions]

PR summary d61e514b58

Import changes for modified files

No significant changes to the import graph

Import changes for all files

Files	Import difference

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Declarations diff

No declarations were harmed in the making of this PR! 🐙

You can run this locally as follows

## summary with just the declaration names:
./scripts/declarations_diff.sh <optional_commit>

## more verbose report:
./scripts/declarations_diff.sh long <optional_commit>

The doc-module for script/declarations_diff.sh contains some details about this script.

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No changes to technical debt.

You can run this locally as

./scripts/technical-debt-metrics.sh pr_summary

• The relative value is the weighted sum of the differences with weight given by the inverse of the current value of the statistic.
• The absolute value is the relative value divided by the total sum of the inverses of the current values (i.e. the weighted average of the differences).

[jsm28]

The new file seems to be in a random order. Since this project doesn't have a fixed order (theorem 1, theorem 2, ...), I'd suggest sorting it either alphabetically by theorem name (whether by Unicode collation or code-point order) or numerically by Wikidata code. (The 1000-plus data includes MSC codes, and use of those would be reasonable to provide more structure in the list on our website rather than having a purely alphabetical list there, but I'm not sure if sorting by MSC code would make so much sense for this source file.)

[grunweg]

Good catch! You were right (the old file depended on file system order in some sense); I've added sorting by wikidata ID now.

[fpvandoorn]

Some of the titles contain unicode-escapes, e.g. \u2013.

[grunweg]

Some of the titles contain unicode-escapes, e.g. \u2013.

That's added by the yaml generation script. I'll see if there's an option to output unicode instead.

[grunweg]

Updated and rebased now. This is ready for review again.

[grunweg]

For cross-reference: 1000-plus/1000-plus.github.io#6 and 1000-plus/1000-plus.github.io#7.