fix(signUpModal) : redesign modal + export css modal

...ents/modal-confirmation/modal-confirmation.component.html

...ents/modal-confirmation/modal-confirmation.component.scss

...hared/components/signup-modal/signup-modal.component.html

...hared/components/signup-modal/signup-modal.component.scss

.../shared/components/signup-modal/signup-modal.component.ts

src/assets/scss/_z-index.scss

src/styles.scss