Rename flags in `report_checks`

[akashlevy]

Resolves #126

• [x] Find and replace group_count with group_path_count globally in repo
• [x] Find and replace endpoint_count with endpoint_path_count globally in repo
• [x] Ensure that replacements result in <= 80 char lines
• [x] search/Search.tcl: Add new flag names, deprecation warning on old flag names
• [x] doc/messages.txt: Add new deprecation warnings and update line numbers
• [x] doc/OpenSTA.odt, doc/OpenSTA.pdf: Update flags in docs

[akashlevy]

Here's the test case I used to validate. Let me know if I should add it to the test/ directory in a commit. I assume you already have some report_checks test cases which it might be redundant with, so I didn't include it.

# report_checks with -group_path_count and -endpoint_path_count
read_liberty ../examples/sky130hd_tt.lib.gz
read_verilog verilog_attribute.v
link_design counter
create_clock -name clk -period 10 clk
set_input_delay -clock clk 0 [all_inputs -no_clocks]

puts {report_checks -endpoint_count 2}
report_checks -endpoint_count 2
puts {report_checks -group_count 3}
report_checks -group_count 3
puts {report_checks -endpoint_count 4 -group_count 5}
report_checks -endpoint_count 4 -group_count 5
puts {report_checks -endpoint_path_count 6}
report_checks -endpoint_path_count 6
puts {report_checks -group_path_count 7}
report_checks -group_path_count 7