WLR simplified build scripts, actions and structure

[assambar]

As we bumped WASI SDK and the major runtimes to the latest versions there was a lot of copy-pasting and dealing with mind boggling things in the build scripts.

This PR aims to reduce this for future changes.

• All target folders follow the v${MAJOR}.${MINOR}.${BUILD} format now, as the actual source tag is described in wlr-env-repo.sh file. (for example php/php-8.2.0 would be moved to php/v8.2.0). This immensely simplifies GH actions.
• All build scripts prepare the necessary assets into the build-output root now (instead of complex, highly customizable GH Actions doing this for different flavors)
• GH actions are simplified to dealing with *.{gz,wasm,txt} files instead of complex names. Reusable stuff is extracted in callable workflows
• All flavor targets are handled by GNU Make (instead of folders with symlinks or copy pasted scripts). Note that all wlr-build.sh scripts now have to consider the WLR_BUILD_FLAVOR variable if they want to handle different flavors.
• Developer notes were moved from README.md to docs/developers.md and updated

Note: There is more that could be generalized/simplified but I had to draw the line. The change is already way too big and time consuming for the value it brings.

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Here is what the release builds for the major runtimes look now

• PHP - https://github.com/assambar/webassembly-language-runtimes/actions/runs/5544329413
• Python - https://github.com/assambar/webassembly-language-runtimes/actions/runs/5544330853
• Ruby - https://github.com/assambar/webassembly-language-runtimes/actions/runs/5544332188

And here are samples for the published releases:

• PHP - https://github.com/assambar/webassembly-language-runtimes/releases/tag/php%2F8.2.6%2B20230713-c7dee9a
• Python - https://github.com/assambar/webassembly-language-runtimes/releases/tag/python%2F3.11.4%2B20230713-c7dee9a
• Ruby - https://github.com/assambar/webassembly-language-runtimes/releases/tag/ruby%2F3.2.2%2B20230713-c7dee9a

[ereslibre]

Thank you @assambar. I think this approach is fine, and it will help with maintenance moving forward.

[ereslibre]

This is great, thank you @assambar! I love the direction, and I think is worth getting merged and continuing evolving as we see need.

[Angelmmiguel]

This is a huge and amazing refactor! I believe the build experience is now more consistent and simpler. Congrats on this work! 👏