Add front-end Electron application for Khoj local file syncing (#473)

* Initial version - setup a file-push architecture for generating embeddings with Khoj
* Use state.host and state.port for configuring the URL for the indexer
* Fix parsing of PDF files
* Read markdown files from streamed data and update unit tests
* On application startup, load in embeddings from configurations files, rather than regenerating the corpus based on file system
* Init: refactor indexer/batch endpoint to support a generic file ingestion format
* Add features to better support indexing from files sent by the desktop client
* Initial commit with Electron application
- Adds electron app
* Add import for pymupdf, remove import for pypdf
* Allow user to configure khoj host URL
* Remove search type configuration from index.html
* Use v1 path for current indexer routes

src/interface/desktop/preload.js

@@ -0,0 +1,49 @@
+window.addEventListener('DOMContentLoaded', () => {
+    const replaceText = (selector, text) => {
+      const element = document.getElementById(selector)
+      if (element) element.innerText = text
+    }
+
+    for (const dependency of ['chrome', 'node', 'electron']) {
+      replaceText(`${dependency}-version`, process.versions[dependency])
+    }
+})
+
+const { contextBridge, ipcRenderer } = require('electron');
+
+contextBridge.exposeInMainWorld('electronAPI', {
+  setTitle: (title) => ipcRenderer.send('set-title', title)
+})
+
+contextBridge.exposeInMainWorld('storeValueAPI', {
+    getStoreValue: (key) => ipcRenderer.invoke('getStoreValue', key)
+})
+
+contextBridge.exposeInMainWorld('getFilesAPI', {
+    getFiles: () => ipcRenderer.invoke('getFiles')
+})
+
+contextBridge.exposeInMainWorld('getFoldersAPI', {
+    getFolders: () => ipcRenderer.invoke('getFolders')
+})
+
+contextBridge.exposeInMainWorld('updateStateAPI', {
+    onUpdateState: (callback) => ipcRenderer.on('update-state', callback)
+})
+
+contextBridge.exposeInMainWorld('removeFileAPI', {
+    removeFile: (filePath) => ipcRenderer.invoke('removeFile', filePath)
+})
+
+contextBridge.exposeInMainWorld('removeFolderAPI', {
+    removeFolder: (folderPath) => ipcRenderer.invoke('removeFolder', folderPath)
+})
+
+contextBridge.exposeInMainWorld('hostURLAPI', {
+    setURL: (url) => ipcRenderer.invoke('setURL', url),
+    getURL: () => ipcRenderer.invoke('getURL')
+})
+
+contextBridge.exposeInMainWorld('syncDataAPI', {
+    syncData: () => ipcRenderer.invoke('syncData')
+})