Added the Add* function for the missing Builtin operator Fill

[dmpiergiacomo]

Fixes #48145

Added the Add* function for the missing Builtin operator Fill in TFLM. I can now consume Fill op in my Cortex-M micro-controller.

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[abattery]

@advaitjain coud you review this PR?

[dmpiergiacomo]

Hi @abattery and @advaitjain,

I was not aware of the contributing guidelines for TFLM. I have just opened the issue 48145 to be linked with this PR. I'm still in the process of learning your guidelines, I'll try now to link PR and Issue.

Thanks for your help.

[dmpiergiacomo]

@googlebot I signed it!