Resolve various warnings

[ariostas]

I fixed a bunch of different warnings including the ones from #18 and #19. Also fixed a warning for an unused import in footer.js, the hsf logo not being square, and useEffect having a missing dependency. Also fixed the typos mentioned in #32. Lastly, I modified the iris-hep svg file to more closely match the HSF one and since the clickable area used to be huge.

The last remaining warning I get is this one, which was also mentioned in #21. But I think it might be trickier to fix it since it's coming from other dependencies.

warn `isModuleDeclaration` has been deprecated, please migrate to `isImportOrExportDeclaration`
    at isModuleDeclaration (/Users/ariostas/Documents/HSF-training/training-center-aniket/node_modules/@babel/types/lib/validators/generated/index.js:2748:35)
    at PluginPass.Program (/Users/ariostas/Documents/HSF-training/training-center-aniket/node_modules/babel-plugin-lodash/lib/index.js:102:44)

Closes #18
Closes #19
Closes #32

[klieret]

Thanks so much, that's a lot of things in one PR!