Add a customizable logo to QR (#1955)

* add QR_LOGO variable
* add logo to images folder
* css for overlaying logo on qr
* qr url on settings
* add qr url to global env
* add QR url input on theme tab in adminUI
* new component added
* use svg
* remove white border around logo in the QR

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Co-authored-by: Pavol Rusnak <pavol@rusnak.io>
Co-authored-by: dni ⚡ <office@dnilabs.com>

lnbits/static/images/logos/lnbits.svg

@@ -0,0 +1,19 @@
+<svg width="900" height="900" viewBox="0 0 900 900" fill="none" xmlns="http://www.w3.org/2000/svg">
+<g filter="url(#filter0_i_10_29)">
+<circle cx="450" cy="450" r="450" fill="#1E1E1E"/>
+</g>
+<path d="M387.802 476.423L281.613 730.887L584.54 389.763H459.418L619.113 168.387H407.558L305.485 476.423H387.802Z" fill="#FF1FE1"/>
+<defs>
+<filter id="filter0_i_10_29" x="-0.1" y="-0.1" width="900.1" height="900.1" filterUnits="userSpaceOnUse" color-interpolation-filters="sRGB">
+<feFlood flood-opacity="0" result="BackgroundImageFix"/>
+<feBlend mode="normal" in="SourceGraphic" in2="BackgroundImageFix" result="shape"/>
+<feColorMatrix in="SourceAlpha" type="matrix" values="0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 127 0" result="hardAlpha"/>
+<feMorphology radius="0.6" operator="dilate" in="SourceAlpha" result="effect1_innerShadow_10_29"/>
+<feOffset dx="-1" dy="-0.4"/>
+<feGaussianBlur stdDeviation="0.35"/>
+<feComposite in2="hardAlpha" operator="arithmetic" k2="-1" k3="1"/>
+<feColorMatrix type="matrix" values="0 0 0 0 1 0 0 0 0 0.121569 0 0 0 0 0.882353 0 0 0 1 0"/>
+<feBlend mode="normal" in2="shape" result="effect1_innerShadow_10_29"/>
+</filter>
+</defs>
+</svg>