Json5ProtocolReader (1): Implement main functionalities

Summary:
# Json5ProtocolReader

**JSON/JSON5 deserialization for Thrift values.**

`Json5ProtocolReader` provides a Thrift protocol reader interface that parses JSON5 or "basic" JSON input:

* **"JSON5"** refers to the "JSON5 Data Interchange Format (version 1.0.0/March 2018)" as defined in [spec.json5.org](https://spec.json5.org/). It is a subset of ECMAScript 5.1 ([262.ecma-international.org/5.1](https://262.ecma-international.org/5.1/)).
* **"Basic JSON"** refers to the "JavaScript Object Notation (JSON) Data Interchange Format" as defined in RFC7159 ([datatracker.ietf.org/doc/html/rfc7159](https://datatracker.ietf.org/doc/html/rfc7159)).

The API of this class is modeled after `SimpleJSONProtocolReader`.

## Current status

> **EXPERIMENTAL:** The output is unstable and there are missing features. APIs may break with no prior notice. USE AT YOUR OWN RISK (preferably NOT IN PRODUCTION).

## Compatibility Features

To support backward compatibility with existing JSON formats, this reader accepts multiple input formats for certain types:

### Bool Fields

- Accepts both true/false bare literals and quoted strings: `true`, `"true"`

### Integer Fields

* Accepts both JSON numbers and quoted strings: `42` and `"42"`

### Floating-Point Fields

* Accepts both JSON numbers and quoted strings: `3.14` and `"3.14"`
* Supports NaN and Infinity as bare literals or quoted: `NaN`, `"NaN"`, `Infinity`, `"Infinity"`, `-Infinity`, `"-Infinity"`

## Unimplemented types

* Enum
* Map

Reviewed By: iahs

Differential Revision: D95174817

fbshipit-source-id: 327ca0baed959c3a8fef07d48d063f3fc1896763

Author: Mizuchi

third-party/thrift/src/thrift/lib/cpp2/protocol/Protocol.h

@@ -118,6 +118,7 @@ struct SkipNoopString {
   void append(const char*, size_t) {}
   void clear() {}
   void reserve(size_t) {}
+  void operator=(std::string_view) {}
 };
 
 // Checks if bool hold a valid value (true or false) and throws exception