feat: Add a EdgeRateLimiter JavaScript Class which enables edge-rate-limiting by utilising a RateCounter and a PenaltyBox instance (#732)

Author: JakeChampion

documentation/docs/fastly:edge-rate-limiter/EdgeRateLimiter/EdgeRateLimiter.mdx

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+---
+hide_title: false
+hide_table_of_contents: false
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+---
+# `EdgeRateLimiter()`
+
+The **`EdgeRateLimiter` constructor** lets you open an epen a [ERL](https://docs.fastly.com/products/edge-rate-limiting) with the given ratecounter and penaltybox.
+
+
+>**Note**: Can only be used when processing requests, not during build-time initialization.
+
+## Syntax
+
+```js
+new EdgeRateLimiter(rateCounter, penaltyBox)
+```
+
+> **Note:** `EdgeRateLimiter()` can only be constructed with `new`. Attempting to call it without `new` throws a [`TypeError`](../../globals/TypeError/TypeError.mdx).
+
+### Parameters
+
+- `rateCounter` _: RateCounter_
+  - The RateCounter instance to associate with this EdgeRateLimiter instance
+- `penaltyBox` _: PenaltyBox_
+  - The PenaltyBox instance which should be associated with this EdgeRateLimiter instance
+
+### Return value
+
+A new `EdgeRateLimiter` object.
+
+### Exceptions
+
+- `TypeError`
+  - Thrown if the provided rateCounter value is not an instance of RateCounter
+  - Thrown if the provided penaltyBox value is not an instance of PenaltyBox
+

documentation/docs/fastly:edge-rate-limiter/EdgeRateLimiter/prototype/checkRate.mdx

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+---
+hide_title: false
+hide_table_of_contents: false
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+---
+# EdgeRateLimiter.prototype.checkRate
+
+Increment an entry in the rate counter and check if the entry has exceeded some average number of requests per second (RPS) over the given window.
+If the entry is over the RPS limit for the window, add to the penaltybox for the given `timeToLive`.
+
+Valid `timeToLive` is 1 minute to 60 minutes and `timeToLive` value is truncated to the nearest minute.
+
+## Syntax
+```js
+checkRate(entry, delta, window, limit, timeToLive)
+```
+
+### Parameters
+
+- `entry` _: string_
+  - The name of the entry to increment and check
+- `delta` _: number_
+  - The amount to increment the `entry` by
+- `window` _: number_
+  - The time period to check across, has to be either 1 second, 10 seconds, or 60 seconds
+- `limit` _: number_
+  - The requests-per-second limit
+- `timeToLive` _: number_
+  - In minutes, how long the entry should be added into the penalty-box
+  - Valid `timeToLive` is 1 minute to 60 minutes and `timeToLive` value is truncated to the nearest minute.
+
+
+### Return value
+
+Returns `true` if the entry has exceeded the average RPS for the window, otherwise returns `false`.
+
+### Exceptions
+
+- `TypeError`
+  - Thrown if the provided `name` value can not be coerced into a string
+  - Thrown if the provided `delta` value is not a positive finite number.
+  - Thrown if the provided `window` value is not either, 1, 10, or 60.
+  - Thrown if the provided `limit` value is not a positive finite number.
+  - Thrown if the provided `timeToLive` value is not either, a number between 1 and 60 inclusively.
+