[Uim] Focus and cursor position shift handlings (bug #7729)

[YAMAMOTO Kengo / YamaKen]

Hi all,

I think that it's a good time to add focus and cursor position
shift handlings to input contexts because uim API is already
revised by the recent text acquisition feature. Aggregating such
interface addition will reduce total development cost.

Could anyone contribute your time to implement this feature? 
I can offer API suggestion, documentation and responses to
discussion.

Adding these handlers in addition to the existing reset handler
is supposed. Code modifications for bridges, libuim, and each IM
are needed to support it.

- focus in/out
- cursor relocation

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YAMAMOTO Kengo / YamaKen  yamaken at bp.iij4u.or.jp
FAMILY   Given / Nick