Change "Select as" behaviour in the "Coin Control" page

[evanlinjin]

Default coin states:

First, remove "please select".

• For UNSPENT coins; "Candidate" is default.
• For SPENT coins; "Ignored" is default.

Batch-select buttons:

• Ignore All (set all SPENT and UNSPENT coins as "Ignored").
• Select all UTXOs as candidates (set all UNSPENT coins as "Candidate").