feat(common): broaden types in StreamableFile constructor

[jonahsnider]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/nestjs/nest/blob/master/CONTRIBUTING.md
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Other... Please describe:

What is the current behavior?

Issue Number: N/A

The StreamableFile constructor supports using a NodeJS.Buffer when passing a buffer (as opposed to a readable stream).

What is the new behavior?

The StreamableFile constructor accepts a Uint8Array when passing a buffer.
The parameter is checked using util's types.isUint8Array function, added in Node.js v10.0.0.

Does this PR introduce a breaking change?

• Yes
• No

Other information

NodeJS.Buffer extends Uint8Array so this will not affect existing code that uses NodeJS.Buffer instances.

Supporting broader types for parameters is generally good because it makes it easier for developers to take advantage of Nest's features.

Specifically, allowing Uint8Arrays in addition to NodeJS.Buffers makes it much easier to pass data buffers from WASM directly to StreamableFile without needing to pass them through Buffer.from beforehand.

[jmcdo29]

Code looks good to me. Thanks for updating the tests too

[jonahsnider]

Unfortunately the tests are failing due to some very confusing behavior from chai:

Trying to fix them currently...
Fixed.

[coveralls]

Pull Request Test Coverage Report for Build ab37a701-e40b-44ab-8605-d94a0aae68f6

• 2 of 2 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.001%) to 94.131%

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Totals
Change from base Build 6f937466-75ef-49c3-bc59-e84e673d5fb1:	0.001%
Covered Lines:	5694
Relevant Lines:	6049

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💛 - Coveralls

[micalevisk]

@jonahsnider could you leverage on this to run npm run format and commit packages/common/file-stream/streamable-options.interface.ts file as well? 😄