Add svg import conversion tool

[mlm-games]

Closes godotengine/godot-proposals#12770.

This PR adds a new tool to the Project > Tools menu (currently titled: "Convert SVG Import Files from Texture2D to SVGTexture") . When run, it finds all of the svg files in the project and converts their importer to SVGTexture from Texture2D, causing the oversampling feature work for them.

Here is an adapted project where i had imported the editor icons used in the main scene to Texture2D
adapted_test_project.zip

The code in this PR is adapted from the "Upgrade Project Files..." tool (ProjectUpgradeTool in the source code, and the pr format has been adapted from the Add UID upgrade tool PR ).

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Had initially thought of doing this for my project which had a lot of svg files that were still imported as CompressedTexture2Ds in 4.5-beta3 (makes sense, if using custom import settings that can't be used currently and do not want them being erased). I didn't have any such import settings so thought of making an tool that helps with the conversion...

[AThousandShips]

Thanks for opening a pull request!

Feature pull requests should be associated to a feature proposal to justify the need for implementing the feature in Godot core. Please open a proposal on the Godot proposals repository (and link to the proposal in this pull request's body).

[mlm-games]

Thanks for opening a pull request!

Feature pull requests should be associated to a feature proposal to justify the need for implementing the feature in Godot core. Please open a proposal on the Godot proposals repository (and link to this pull request in the proposal's body).

Oops, added it (sorry, is my first pr here; thought the pr used for reference just closed the issue)

[mlm-games]

Fixed pre-commit lint

[fire]

This feels like an gdscript addon but it would be cool to standardize importer to importer conversions with this as the first usage. Hmm