Improve the guest language documentations

[vigoo]

Currently we have the following documentation for supported guest languages:

"Building components"
=>  "Tier N"
=> => "Language"

For each the structure currently is basically:

• Required tools
• Very small mention of ability to use golem-cli new
• Detailed description of how to do everything by hand from zero
• For Rust there is a mention of golem-rust
• For Rust and Go there is a section of how to do HTTP
• For JS and TS there is a small section about how to use additional WIT dependencies but not much details

I propose the following changes:

• Structure the page so that people arrive immediately to the list of Tier 1 languages, and keep the other few supported ones in somewhere deeper in the tree
• For each Tier 1 language, have the following sections:
  • Prerequisites (what to install and how) - should be prepared to have docs for more than just OSX
  • Quickstart with golem-cli with a concrete example from 0 to having the WASM (we should have a default 'getting started' example in golem-examples for each tier 1 language)
  • Section about how to export interfaces, custom data types and resources (whether requires editing WIT and where to put it, and how it looks in code)
  • Section about importing interfaces
  • Section about using HTTP (in Rust and Go it should only mention the reqwest/go libraries)
  • Section about using the transaction API (in Rust refer to the golem-rust lib, for others now just build on the previous sections on how to import it - explanation of the API is on the separate top level page)
• In other top level pages (Worker to Worker communication, Transactions, Promises) make sure to:
  • They describe the general concept and usability in a language-independent way
  • They link to the appropriate parts of the restructured guest language pages to learn how to use them in each language
  • There should be a golem-cli new ... example for each of these for each supported language that provides a good starting point and example people can look at
  • Maybe we could have per-language sub pages highlighting parts of these examples so it is also browsable as part of the webpage and not just if you generate it for yourself