feat: add sidechain-specific RPCs/sugar (#1940)

* federator_info responses/requests

* edit docstring

* make strings narrower

* export federator_info

* implement createXchainPayment

* add tests

* fix dependency cycle

* fix linter errors

* rename xchain -> crosschain

* rename more

* edit HISTORY

* fix docstrings

* add another test

packages/xrpl/src/utils/stringConversion.ts

@@ -0,0 +1,27 @@
+/**
+ * Converts a string to its hex equivalent. Useful for Memos.
+ *
+ * @param string - The string to convert to Hex.
+ * @returns The Hex equivalent of the string.
+ * @category Utilities
+ */
+function convertStringToHex(string: string): string {
+  return Buffer.from(string, 'utf8').toString('hex').toUpperCase()
+}
+
+/**
+ * Converts hex to its string equivalent. Useful to read the Domain field and some Memos.
+ *
+ * @param hex - The hex to convert to a string.
+ * @param encoding - The encoding to use. Defaults to 'utf8' (UTF-8). 'ascii' is also allowed.
+ * @returns The converted string.
+ * @category Utilities
+ */
+function convertHexToString(
+  hex: string,
+  encoding: BufferEncoding = 'utf8',
+): string {
+  return Buffer.from(hex, 'hex').toString(encoding)
+}
+
+export { convertHexToString, convertStringToHex }