Fix Search Bar Text Related Alignment.

[ShaopengLin]

Fix #594

Changes:

1. Text in the search bar aligns to the right if using RTL and to the left if using LTR. This aligns with the suggestion.
2. Placeholder text in the search bar aligns according to the same rule.
3. The hint (fulltext-search) in suggestions shouldn't naively append to text, as depending on the text it is treated differently. Adding special direction marks can fix the direction it is appended.

I tested by using reverse mode as well as changing my system locale to Arabic.