2b37583ca5 test: add test for push slice minimal (ChrisCho-H)
Pull request description:
Following https://github.com/rust-bitcoin/rust-bitcoin/pull/4322.
Test `push_slice` and `push_slice_nom_minimal` from OP_1...OP_16 and OP_1NEGATE.
ACKs for top commit:
apoelstra:
ACK 2b37583ca55195965ce2f129d75a1fc114d8b5f6; successfully ran local tests
Tree-SHA512: 6d8e96d522d317d7ede2f1bc133050d98ccbc1816c59fe3589003de249828367314f751d3a75d6b58b0c90b1b735f85650c0d7acebaf5da21a38fb651ab4177d