fix: patch to direction:rtl flipped the content. fixing logic instead

[eyal-elkevity]

• Please check if the PR fulfills these requirements

• The commit message follows our guidelines
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)
• Unit tests are passing ng test
• Lint tests are passing ng lint

• What kind of change does this PR introduce? (Bug fix, feature, docs update, ...)
  bug fix

• What is the current behavior? (You can also link to an open issue here)
  after my last commit to support direction:rtl, Move functions worked but the content got flipped. See I wanted to keep the existing "math" logic and just trick the browser... but the content got flipped. so I removed the flipping code and instead changed the scrollLeft calcs to support negatives (it was just 3 tiny places. rest of commit is actually removing of the old fix).

• What is the new behavior (if this is a feature change)?

• Does this PR introduce a breaking change? (What changes might users need to make in their application due to this PR?)
  no

• Other information:

[eyal-elkevity]

I've added another commit to this PR, sorry I thought it would create a new one. it's just that if you don't use scrollbar-hidden="true" - when calling moveTo() with a high number (like in the demo, click the "last" button) - it actually moves the index there, because calculating the containerWidth fails. This happens since neither local members "wrapper" nor "parentNode" are initialized. so not to harm existing code - I didn't force any initialization - just added another "||" to the width calculation with the actual parent.

[eyal-elkevity]

ok nm I've reverted the scrollbar patch because a test fails, seems to be that in test mode the moveTo fails, not sure why. it's late for me so I'd rather just revert and have this PR focus on the direction:rtl anyways. sorry...

[bfwg]

Should we revert #293?

[eyal-elkevity]

Should we revert #293?

well actually this commit cleans the code from that commit and introduces an actual fix to direction:rtl

[bfwg]

LGTM