[NEW FEATURE] provide Flex element in uikit to be used in apps

[Firdausia Fatima]

Block should extend the block type to have div type too. which can either be flex or block type.
Definition for div block will be in file apps-engine> src>definition>uikit>blocks>blocks.ts
export interface IDivBlock { type: BlockType.DIV; flex : boolean; elements: Array<IBlock> }

inside Block builder a new function can be added
public addDivBlock(block: DivBlockParam): BlockBuilder { this.addBlock({type:BlockType.DIV, ...block} as IDivBlock); return this; }
however I'm not sure where I've to write html for the element in fuselage or anywhere else.Kindly guide me.