[TIMOB-11510] reproxy subviews of tableview rows when className specified

[mstepanov]

TIMOB-11510

Test instructions:

1. use example project attached to the JIRA.
2. ensure smooth scrolling performance comparing to before the fix.
3. use Instruments/Core Animation to measure FPS during scrolling for comparison.
4. use Instruments/Allocations to ensure number of allocated TiUILabel, UILabel, TiUITableViewRowContainer is not increasing as table scrolls.

Test another example in JIRA comments. Ensure ERROR messages printed to console.

Test for regressions with TIMOB-9500 and TIMOB-5429

[mstepanov]

@BlainHamon ready for CR+FR

[WhichKatieDid]

Note to self. We really should consider a childrenCount property to shortcut the copying that would be done here if the counts differ.

[mstepanov]

@BlainHamon these used not only for counts, but actual iterations too.

[WhichKatieDid]

CR tentative. I really don't feel comfortable with the area around the line note, given how expensive children can be.

[WhichKatieDid]

FR inconclusive. Couldn't tell speed difference, although it looks like no objects are accruing or leaking.

[WhichKatieDid]

Retesting with iPad 1.

[WhichKatieDid]

Still can't tell the difference. Added to that, the sample code provided keeps reporting [WARN] Hex color passed looks invalid: with a blank string. Do suggest adding a childrenCount accessor to TiViewProxy, using that where possible, to avoid using the expensive children accessor unless actually needed. Needs addressing.