Feat: Add input for uploading banner

[AshutoshDash1999]

Is your feature request related to a problem? Please describe.
The banner is static for now and hence can't be changed with new image.

Describe the solution you'd like
When someone will click on the existing banner a window will open to choose a file and select that banner.

Additional context

• The upload button will shifted to bottom right and on top of banner.
• The max file size will be 2MB and minimum dimension should be 1600 x 400

Please assign this issue to me under GSSOC 24.

[SUGAM-ARORA]

@AshutoshDash1999 Issue has been assigned to you

[AshutoshDash1999]

hi @SUGAM-ARORA I think this should be level 3 as I am adding completely new feature and not just improving existing ones.

[AshutoshDash1999]

@SUGAM-ARORA please review this PR: #67

[SUGAM-ARORA]

@AshutoshDash1999 I assigned it as level 2 based on its complexity and time consumption

[SUGAM-ARORA]

@SUGAM-ARORA please review this PR: #67

Successfully merged it. Great work