feat: Add missing mod.ts files in std (#3509)

std/archive/tar.ts:
- Remove FileReader.
- Remove FileWriter.

std/encoding/csv.ts:
- ExtendedParseOptions -> ParseOptions
- HeaderOption -> HeaderOptions
- ParseOptions -> ReadOptions
- readAll() -> readMatrix()

std/encoding/yaml.ts:
- DumpOptions -> StringifyOptions

std/fmt/colors.ts:
- getEnabled() -> getColorEnabled()
- setEnabled() -> setColorEnabled()

std/testing/mod.ts:
- Re-export sibling modules.

std/encoding/mod.ts

@@ -0,0 +1,14 @@
+export {
+  HeaderOptions as CsvHeaderOptions,
+  ParseError as CsvParseError,
+  ParseOptions as ParseCsvOptions,
+  parse as parseCsv
+} from "./csv.ts";
+export {
+  decode as decodeHex,
+  decodeString as decodeHexString,
+  encode as encodeToHex,
+  encodeToString as encodeToHexString
+} from "./hex.ts";
+export { parse as parseToml, stringify as tomlStringify } from "./toml.ts";
+export { parse as parseYaml, stringify as yamlStringify } from "./yaml.ts";