Add copyright attribution metadata to icon.svg

[nathanfranke]

See also: #61955 (comment)

TODO

• as bruvzg mentioned, this PR should actually change editor/icons/DefaultProjectIcon.svg, not icon.svg.
• I am not sure if <dc:date>2017</dc:date> is correct or if Copyright (c) 2017 should be used somewhere.
• Fix potential CI/CD bug (see below)

---

Edit: Was a comment (<!-- -->), but now it is SVG metadata.

SVG metadata resources:

• https://svgo.dev/docs/plugins/removeMetadata/
• https://www.w3.org/TR/SVGTiny12/metadata.html#metadataElementExample
• https://opensource.creativecommons.org/ccrel/

CI/CD: Possible SVGO bug

• svg/svgo#431
• svg/svgo#1609

SVGO strips the metadata unless both these overrides are present. However, this incorrectly also whitelists editor metadata like xmlns:inkscape.

diff --git a/misc/utility/svgo.config.mjs b/misc/utility/svgo.config.mjs
index 3849103e2b..10ba9063d5 100644
--- a/misc/utility/svgo.config.mjs
+++ b/misc/utility/svgo.config.mjs
@@ -12,6 +12,8 @@ export default {
                                overrides: {
                                        removeHiddenElems: false,
                                        convertPathData: false,
+                                       removeEditorsNSData: false,
+                                       removeMetadata: false,
                                },
                        },
                },

A possible workaround is using scour or another optimizer.

scour --no-line-breaks icon.svg > _icon.svg && mv _icon.svg icon.svg

In the meantime, I enabled pretty print so the diff is easier to view.

svgo icon.svg --config misc/utility/svgo.config.mjs --pretty

[bruvzg]

It is attributed in the COPYRIGHT.txt, so not sure if there's any point of duplicating it.

But probably makes sense for the default project icon, which is added to user projects.

[bruvzg]

.pre-commit-config.yaml can have exclude to skip check for a specific file:

        files: \.svg$
        args: [--quiet, --config, misc/utility/svgo.config.mjs]
        additional_dependencies: [svgo@3.3.2]
+        exclude: |
+          (?x)^(
+            editor/icons/DefaultProjectIcon.svg
+          )$

      - id: copyright-headers
        name: copyright-headers