fix: Fix runnables being incorrectly constructed
I've misunderstood parts of the code here which caused runnables to arbitrarily break :) (I have yet to understand the conditions that made them break though, there is some odd caching involved I feel like ...)
Fixes https://github.com/rust-lang/rust-analyzer/issues/17402
internal: Clean up runnable lsp extension
This feels like a natural addition to me, and also allows us to drop the expect-test hardcoding from the extension. Additionally, `cargoExtraArgs` is pointless, all the client will do is merge it with `cargoArgs` so the server can do that instead of delegating that to the client.
feat: Add landing/faq walkthrough pages
This is a basic implementation of a landing and FAQ page; I've included the bare-bones information as well as a [recommended section on inlay hints](446135321).
I've also added `rust-analyzer: Open Walkthrough` and `rust-analyzer: Open FAQ` commands for ease of access.
I am hoping to create a small list of FAQ to include that might be useful as well as any other information I may have missed in the landing page. Feel free to share any suggestions!

cc #13351
feat: add `toggleLSPLogs` command
Implement client-side command to toggle LSP logs in VSCode.
The command replaces the need to add/remove the `"rust-analyzer.trace.server": "verbose"` setting each time one wants to display logs. I've also updated the docs/ instances that reference the now outdated manual method.
The command labeled `rust-analyzer: Toggle LSP Logs` enables the setting project-wide and opens the relevant trace output channel.
Closes#8233
Refactor extension to support arbitrary shell command runnables
Currently, the extension assumes that all runnables invoke cargo. Arguments are sometimes full CLI arguments, and sometimes arguments passed to a cargo subcommand.
Refactor the extension so that tasks are just a `program` and a list of strings `args`, and rename `CargoTask` to `RustTask` to make it generic.
(This was factored out of #16135 and tidied.)
We can't tell vscode to not add in the extra indentation, so we instead opt to remove it from the edits themselves, and then let vscode add it back in.