[Open Assets] srb2bld - SRB2 Build/Package manager CLI

• Corrected name of SRB2 Kart's directory for finding proper path to assets,
• Replaced libpng to libpng12 for Musl-based Linux distros for better compatibility,
• Changed name of GNU Stow's libpng12-lib32 directory to libpng12 (if you have installed libpng12 in /usr/local/stow/libpng12-lib32 path, it is recommended to do sudo -E STOW_DIR=/usr/local/stow stow -Dv libpng12-lib32 && sudo mv -v /usr/local/stow/libpng12-lib32 /usr/local/stow/libpng12 && sudo -E STOW_DIR=/usr/local/stow stow -v libpng12, to prevent getting issues with compiling builds in the future),
• Improved detection of missing libraries for Musl-based Linux distros,
• Added patchelf command to fix compiled SLADE for Musl-based Linux distros,
• Corrected messages,
• Removed unused code.

• Updated compatibility table,
• Fixed issue of not finding compiled files which belong to root on Alpine Linux,
• Fixed issue of missing patch.pk3 file for compiled SRB2 VR,
• Fixed issue of not finding compiled SRB2 2.1 Legacy binary, to copy it to path,
• Fixed issue of not to be able to convert srb2win.ico file to PNG format for SRB2 2.0 and SRB2 Final Demo,
• Some checks to prevent downloading libopenmpt and libgme source codes when building wadcli and SLADE,
• Fixed issue of missing ipx.h file when compiling SRB2 2.0 on Alpine Linux,
• Fixed issue of missing sdl-dev package for Alpine Linux container.

• Fixed issue of getting changed name of build's configuration folder after update,
• Fixed issue with Curl not updating SRB2 Persona file with assets, if file was previously downloaded,
• Other fixes and text correction.

• Changed SRB2 Persona's assets link to make it run with current version of game,
• Removed some unused code.

• Improved detection of missing libraries for Gentoo,
• Changed checking current git branch of build to be more compatible with older than Git 2.22.

• Fixed look of installed SRB2 desktop icons,
• Replaced deprecated method of obtaining GPG keys for apt-fast and gcc packages.

• Fixed "permission denied" issues with Linux distros (Fedora) that have SELinux enabled,
• Fixed proper reading of URLs of some assets within Docker container.

• Fixed permission conflicts of updated Git (since version v2.35) with Docker container.

• Updated SRB2 NetPlus version to 2.2.10,
• Replaced SRB2 NetPlus Git repository from https://git.netplus.friskyfox.art/NetPlus/netplus to https://git.do.srb2.org/JohnFrostFox/netplus .

• Improved detection of missing dependencies for host Linux systems,
• Fixed issue of not choosing proper version of compiler after last update.