Added support to slice a table using percentages

[malhotrashivam]

Feature request, closes #3203

Change description: Added a new slicePct() method that takes percentages, similar to how slice() works with row indexes.

Documentation update: We need to add both java and python documentations, similar to the slice() method.
For Java, the syntax is table.slicePct(double startPercentInclusive, double endPercentExclusive)
For Python, the syntax is table.slice_pct(start_pct:float, end_pct:float)

The function returns a subset of table in the range [startPercentInclusive * sizeOfTable , endPercentExclusive * sizeOfTable). For example, for a table of size 10, slicePct(0.1, 0.7) will return a subset from the second row to the seventh row. Similarly, slicePct(0, 1) would return the entire table (because row positions run from 0 to size-1).
The percentage arguments must be in [0,1], otherwise the function returns an error.
Also, the method is not supported for blink tables and will give an error.

[lbooker42]

Suggested test: Make sure that slices of a table when merged recreate exactly the original table.

Specifically, create a test where you create slices 0.0-0.25, 0.25-0.5, 0.5-0.75, 0.75-1.0 then verify all rows from the main table are in exactly one slice (no duplicates or missing rows).

[jmao-denver]

LGTM

[deephaven-internal]

Labels indicate documentation is required. Issues for documentation have been opened:

How-to: https://github.com/deephaven/deephaven.io/issues/2910
Reference: https://github.com/deephaven/deephaven.io/issues/2909