Support custom model URL

[universeroc]

I want to load a local model rather than tfhub.dev to improve the loading performance. But I can not load model except from tfhub.dev, so I make this patch to make it work, if there's another way to make it let me know, thank you in advance :)

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[ahmedsabie]

Reviewable status: 0 of 1 approvals obtained (waiting on @universeroc)

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toxicity/src/index.ts line 37 at r1 (raw file):

 * `identity_attack` | `insult` | `threat` | `sexual_explicit` | `obscene`.
 * Defaults to all labels.
 * @param modelURL Load a model from URL rather than tfhub.dev

Rephrase it to "URL to load model from. Defaults to tfhub.dev.

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toxicity/src/index.ts line 61 at r1 (raw file):

  }

  setModelURL(url: string) {

Please make this private

[ahmedsabie]

Reviewable status: 0 of 1 approvals obtained (waiting on @universeroc)

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toxicity/src/index.ts line 37 at r1 (raw file):

Previously, ahmedsabie wrote…

Rephrase it to "URL to load model from. Defaults to tfhub.dev.

Sorry I should have been clearer, the argument name should still stay as modelURL, so the whole line should be:

* @param modelURL. URL to load model from. Defaults to tfhub.dev.

Remove the duplicate Defaults to tfhub.dev on the next line as well.

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toxicity/src/index.ts line 41 at r2 (raw file):

 */
export async function load(threshold: number, toxicityLabels: string[],
    URL: 'https://tfhub.dev/tensorflow/tfjs-model/toxicity/1/default/1') {

rename argument back to modelURL

[universeroc]

@ahmedsabie setModelURL should not be set private as in function load call this setModelURL There's no friend keyword like C++ so I remove the private keyword in this commit.