[xc7] Add clock placer

[acomodi]

This PR builds on top of #1232 as a fix for the python linter was needed.

With prjxray ad prjxray-db updated to latest version, containing the clock_region addition, this PR should now go green.

[acomodi]

I think CI is hitting the same issue as in #1222

FAILED: cd /tmpfs/src/github/symbiflow-arch-defs/build/xc7/tests/iobuf_infer/iobuf_infer_basys3/artix7-xc7a50t-virt-xc7a50t-test && /tmpfs/src/github/symbiflow-arch-defs/utils/quiet_cmd.sh /tmpfs/src/github/vtr-verilog-to-routing/build/utils/fasm/genfasm /tmpfs/src/github/symbiflow-arch-defs/build/xc7/archs/artix7/devices/xc7a50t-virt/arch.timing.xml /tmpfs/src/github/symbiflow-arch-defs/build/xc7/tests/iobuf_infer/iobuf_infer_basys3/artix7-xc7a50t-virt-xc7a50t-test/top.eblif --device xc7a50t-test --read_rr_graph /tmpfs/src/github/symbiflow-arch-defs/build/xc7/archs/artix7/devices/rr_graph_xc7a50t_test.rr_graph.real.xml --min_route_chan_width_hint 100 --max_router_iterations 500 --routing_failure_predictor off --router_high_fanout_threshold -1 --constant_net_method route --route_chan_width 500 --clock_modeling route --place_delay_model delta_override --router_lookahead connection_box_map --disable_check_route on --strict_checks off --clustering_pin_feasibility_filter off --allow_dangling_combinational_nodes on --disable_errors check_unbuffered_edges:check_route --congested_routing_iteration_threshold 0.8 --incremental_reroute_delay_ripup off --base_cost_type delay_normalized_length_bounded --astar_fac 1.2 --bb_factor 10 --initial_pres_fac 4.0 --disable_check_rr_graph on --suppress_warnings /tmpfs/src/github/symbiflow-arch-defs/build/xc7/tests/iobuf_infer/iobuf_infer_basys3/artix7-xc7a50t-virt-xc7a50t-test/noisy_warnings.log,sum_pin_class:check_unbuffered_edges:load_rr_indexed_data_T_values:check_rr_node:trans_per_R && /usr/bin/cmake -E copy /tmpfs/src/github/symbiflow-arch-defs/build/xc7/tests/iobuf_infer/iobuf_infer_basys3/artix7-xc7a50t-virt-xc7a50t-test/vpr_stdout.log /tmpfs/src/github/symbiflow-arch-defs/build/xc7/tests/iobuf_infer/iobuf_infer_basys3/artix7-xc7a50t-virt-xc7a50t-test/genhlc.log && /usr/bin/cmake -E copy /tmpfs/src/github/symbiflow-arch-defs/build/xc7/tests/iobuf_infer/iobuf_infer_basys3/artix7-xc7a50t-virt-xc7a50t-test/top.fasm /tmpfs/src/github/symbiflow-arch-defs/build/xc7/tests/iobuf_infer/iobuf_infer_basys3/artix7-xc7a50t-virt-xc7a50t-test/top.genfasm.fasm && cat /tmpfs/src/github/symbiflow-arch-defs/build/xc7/tests/iobuf_infer/iobuf_infer_basys3/artix7-xc7a50t-virt-xc7a50t-test/top.fasm /tmpfs/src/github/symbiflow-arch-defs/build/xc7/tests/iobuf_infer/iobuf_infer_basys3/artix7-xc7a50t-virt-xc7a50t-test/top_fasm_extra.fasm > /tmpfs/src/github/symbiflow-arch-defs/build/xc7/tests/iobuf_infer/iobuf_infer_basys3/artix7-xc7a50t-virt-xc7a50t-test/top.concat.fasm && /usr/bin/cmake -E rename /tmpfs/src/github/symbiflow-arch-defs/build/xc7/tests/iobuf_infer/iobuf_infer_basys3/artix7-xc7a50t-virt-xc7a50t-test/top.concat.fasm /tmpfs/src/github/symbiflow-arch-defs/build/xc7/tests/iobuf_infer/iobuf_infer_basys3/artix7-xc7a50t-virt-xc7a50t-test/top.fasm
/tmpfs/src/github/symbiflow-arch-defs/utils/quiet_cmd.sh: line 9: 13770 Killed                  "$@" > $OUTPUT 2>&1

[acomodi]

@litghost PR went green on all the builds other than Vendor Tools Tests. This is still related, I believe to the fact that a BUFHCE output is illegally crossing a clock region to get to destination.

I need to reproduce locally in order to be sure about it. Anyway, I believe this can be merged