reseting page offset on input data change

[ritikrishu]

What kind of change does this PR introduce? (check one with "x")

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Other... Please describe:

What is the current behaviour? (You can also link to an open issue here)
Suppose my current offset is 10, limit is 10 and I have 100 rows to display. Now when I filter data based on some search or something I am left with 10 or 15 rows. The total count in footer is updated as expected but all rows are disappeared as the offset is not being reset.
issue: #515

What is the new behaviour?
Reset offset to zero(page 1) whenever rows input is changed.

Does this PR introduce a breaking change? (check one with "x")

• Yes
• No

If this PR contains a breaking change, please describe the impact and migration path for existing applications: ...

Other information:
One other approach can be checking if current offset have data to display and then reset offset accordingly.
Basically something like:

recalculatePages(): void {
    this.pageSize = this.calcPageSize();
    this.rowCount = this.calcRowCount();
    // on input data set change switch to the starting page offset, if total rows are lesser than current offset * limit
    if(this.rowCount / this.pageSize < this.offset) { 
      this.offset = 0;
    }
  }

but I think the current PR implementation provides more consistent behaviour.