Move assets into separate folder

frontend/src/assets/scss/bootstrapV5/mixins/_caret.scss

frontend/src/assets/scss/bootstrapV5/mixins/_clearfix.scss

frontend/src/assets/scss/bootstrapV5/mixins/_container.scss

frontend/src/assets/scss/bootstrapV5/mixins/_deprecate.scss

frontend/src/assets/scss/bootstrapV5/mixins/_forms.scss

frontend/src/assets/scss/bootstrapV5/mixins/_gradients.scss

frontend/src/assets/scss/bootstrapV5/mixins/_grid.scss

frontend/src/assets/scss/bootstrapV5/mixins/_image.scss

frontend/src/assets/scss/bootstrapV5/mixins/_list-group.scss

frontend/src/assets/scss/bootstrapV5/mixins/_lists.scss

frontend/src/assets/scss/bootstrapV5/mixins/_pagination.scss

frontend/src/assets/scss/bootstrapV5/mixins/_reset-text.scss

frontend/src/assets/scss/bootstrapV5/mixins/_resize.scss

...nd/src/assets/scss/bootstrapV5/mixins/_screen-reader.scss

...d/src/assets/scss/bootstrapV5/mixins/_table-variants.scss

...nd/src/assets/scss/bootstrapV5/mixins/_text-truncate.scss

frontend/src/assets/scss/bootstrapV5/mixins/_transition.scss

frontend/src/assets/scss/bootstrapV5/mixins/_utilities.scss

frontend/src/assets/scss/bootstrapV5/utilities/_api.scss

frontend/src/assets/scss/bootstrapV5/vendor/_rfs.scss