binder: Implement Set/Get network params (Part 2)

Implement the following Set/Get methods:
1. PskPassphrase
2. WepKeys
3. WepTxKeyIdx

BUG: 1252274
TEST: Ran 'wpa_supplicant_binder_test'
Change-Id: Icfc318352e85778f5a16b92dee58ff7c0f2f9f23
Signed-off-by: Roshan Pius <rpius@google.com>
3 files changed