Unable to upload pre-encoded (base64/hex) blobs

### Celestia Node version

v0.12.1

### OS

N/A

### Install tools

_No response_

### Others

_No response_

### Steps to reproduce it

[The docs](https://docs.celestia.org/developers/node-tutorial#submitting-data) describe that:

> Data can be hex-encoded (`0x...`), base64-encoded (`"..."`), or a plaintext string which will be encoded to base64 (`'Hello There!'`).

Using pre-encoded hex and base64 does not work in this manner.

### Expected result

I would expect hex strings and base64 strings are converted to bytes from their standard representation, instead of the literal ascii values of their already encoded strings.

### Actual result

In actuality, all data is treated as text, and the ascii representations of the arg are converted to the ascii byte values.

### Relevant log output

_No response_

### Notes

https://github.com/celestiaorg/celestia-node/blob/73336eda96510652881080c7b339d0eca7bc4ca1/nodebuilder/blob/cmd/blob.go#L151 here's where the argument is converted into a blob, it doesn't do any check to see if it is already encoded as hex or base64.