feat(flags): added flags

[saiponnada]

Fixes #2184

• This PR contains CSS changes
• This PR does not contain CSS changes

Description

This PR contains following changes,

• Added the new Flag SVG assets
• Created the flag generation script to add flag- prefixes to all flags that are not prefixed already.
• Updated Skin docs.
• Added flag stories to storybook

Notes

• Even though creating a new script (flag generation) violated DRY, imo it's better to separate the icons and flags script as flags is more one time execution script.
• Should we add the attribution to flag-icons?
• There is an unknown flag. Should we keep it?
• Should we restrict min/max widths for these flags?

Screenshots

Checklist

• I verify the build is in a non-broken state
• I verify all changes are within scope of the linked issue

• I regenerated all CSS files under dist folder
• I tested the UI in all supported browsers
• I did a visual regression check of the components impacted by doing a Percy build and approved the build
• I tested the UI in dark mode and RTL mode
• I added/updated/removed Storybook coverage as appropriate

[ArtBlue]

Looks good.