allow specific precompiled images to be rebuilt

[rahulait]

This PR adds the following capability:

Manual workflow inputs for targeted builds — each matrix dimension (driver branch, kernel flavor, dist, LTS kernel) can be filtered to a single value via workflow_dispatch inputs, instead of always building the full matrix.

Force rebuild flag — a new force_rebuild input that bypasses the ghcr.io tag-existence check (nvcr.io is still treated as authoritative). This will enable us to build and push updated images to ghcr.io which then can be published to nvcr.io

[shivakunv]

To override image in staging , we need to change:

precompiled.sh :- 

function imageExists(){
	regctl manifest get $1 --list > /dev/null && return 0 || return 1
} 

We should add an md5sum check between the staging and ghcr repo to verify whether the image is same or not .

[rahulait]

To override image in staging , we need to change:

precompiled.sh :- 

function imageExists(){
	regctl manifest get $1 --list > /dev/null && return 0 || return 1
} 

We should add an md5sum check between the staging and ghcr repo to verify whether the image is same or not .

Fixed this in change https://github.com/NVIDIA/gpu-driver-container/compare/dc1ee9b75cb65c00cb3a4c8a9bf15779e11e53e4..65f583ce429aa61f709a5194346e18009afda582

[shivakunv]

LGTM