Add new features suggested by NR team

[venu-sambarapu-DS]

introduction

As suggested by NR team the following features are going to be added in validly

• Check sorting on latest year or fiscal_year
• check each year have same number of states if state column exists
• check top ten rows have no null values
• check year or fiscal_year is continuous
• Unit column values should be written in lowercase format.
• remove error for "value as Index" in units column
• throw error for date other than dd-mm-yyyy
• values round up to two decimals
• blank cells in value