Revert "Add docs_preprocessor crate to support Zed Docs" (#16880)

Temporarily revert #16700 to deal with this error:

`error: manifest path `../crates/docs_preprocessor/Cargo.toml` does not
exist` as it was causing the docs-preprocessor not to run, meaning
unexpanded templates were showing up in the public docs.

Reverts zed-industries/zed#16700

Release Notes:

- N/A

crates/docs_preprocessor/src/docs_preprocessor.rs

@@ -1,93 +0,0 @@
-use anyhow::Result;
-use mdbook::book::{Book, BookItem};
-use mdbook::errors::Error;
-use mdbook::preprocess::{Preprocessor, PreprocessorContext as MdBookContext};
-use settings::KeymapFile;
-use std::sync::Arc;
-use util::asset_str;
-
-mod templates;
-
-use templates::{ActionTemplate, KeybindingTemplate, Template};
-
-pub struct PreprocessorContext {
-    macos_keymap: Arc<KeymapFile>,
-    linux_keymap: Arc<KeymapFile>,
-}
-
-impl PreprocessorContext {
-    pub fn new() -> Result<Self> {
-        let macos_keymap = Arc::new(load_keymap("keymaps/default-macos.json")?);
-        let linux_keymap = Arc::new(load_keymap("keymaps/default-linux.json")?);
-        Ok(Self {
-            macos_keymap,
-            linux_keymap,
-        })
-    }
-
-    pub fn find_binding(&self, os: &str, action: &str) -> Option<String> {
-        let keymap = match os {
-            "macos" => &self.macos_keymap,
-            "linux" => &self.linux_keymap,
-            _ => return None,
-        };
-
-        keymap.blocks().iter().find_map(|block| {
-            block.bindings().iter().find_map(|(keystroke, a)| {
-                if a.to_string() == action {
-                    Some(keystroke.to_string())
-                } else {
-                    None
-                }
-            })
-        })
-    }
-}
-
-fn load_keymap(asset_path: &str) -> Result<KeymapFile> {
-    let content = asset_str::<settings::SettingsAssets>(asset_path);
-    KeymapFile::parse(content.as_ref())
-}
-
-pub struct ZedDocsPreprocessor {
-    context: PreprocessorContext,
-    templates: Vec<Box<dyn Template>>,
-}
-
-impl ZedDocsPreprocessor {
-    pub fn new() -> Result<Self> {
-        let context = PreprocessorContext::new()?;
-        let templates: Vec<Box<dyn Template>> = vec![
-            Box::new(KeybindingTemplate::new()),
-            Box::new(ActionTemplate::new()),
-        ];
-        Ok(Self { context, templates })
-    }
-
-    fn process_content(&self, content: &str) -> String {
-        let mut processed = content.to_string();
-        for template in &self.templates {
-            processed = template.process(&self.context, &processed);
-        }
-        processed
-    }
-}
-
-impl Preprocessor for ZedDocsPreprocessor {
-    fn name(&self) -> &str {
-        "zed-docs-preprocessor"
-    }
-
-    fn run(&self, _ctx: &MdBookContext, mut book: Book) -> Result<Book, Error> {
-        book.for_each_mut(|item| {
-            if let BookItem::Chapter(chapter) = item {
-                chapter.content = self.process_content(&chapter.content);
-            }
-        });
-        Ok(book)
-    }
-
-    fn supports_renderer(&self, renderer: &str) -> bool {
-        renderer != "not-supported"
-    }
-}