conditions changed according to the requirement

[07Vaishnavi-Singh]

Changes

1. Optmized conditions according to - https://nodejs.org/api/buffer.html#static-method-bufferisbufferobj

2. Only to return true if the obj is string or is not an object or is a null

Related to #453

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[SgtPooki]

We do not want to add any submodules. We also do not want to add a dependency on ipfs-webui in this repo

[07Vaishnavi-Singh]

@SgtPooki Ahh!!!! my bad. I think the submodule got added by mistake in the previous commit. I have changed the condition to be true if

1. obj is null
2. obj is not an object at all
3. If obj is an object then it has to be a string
   and final
4. if it is a string then isBuffer(obj)-> false then it should be a string

Let me know if I got this right

[SgtPooki]

@07Vaishnavi-Singh Thanks so much for contributing. I put together more of what I was looking for in #460, plus a fix for another bug I found.