Add the concept of scope.

[k1LoW]

ref: #545

And disallow remote reads and reads of directories above the working directory by default.

[github-actions]

Code Metrics Report

	main (4f85b8a)	#663 (49c0caa)	+/-
Coverage	70.0%	70.2%	+0.2%
Code to Test Ratio	1:0.7	1:0.7	-0.0
Test Execution Time	3m20s	3m4s	-16s

Details

  |                     | main (4f85b8a) | #663 (49c0caa) |  +/-  |
  |---------------------|----------------|----------------|-------|
+ | Coverage            |          70.0% |          70.2% | +0.2% |
  |   Files             |             52 |             54 |    +2 |
  |   Lines             |           5735 |           5878 |  +143 |
+ |   Covered           |           4014 |           4128 |  +114 |
- | Code to Test Ratio  |          1:0.7 |          1:0.7 |  -0.0 |
  |   Code              |          11499 |          11738 |  +239 |
+ |   Test              |           8153 |           8209 |   +56 |
+ | Test Execution Time |          3m20s |           3m4s |  -16s |

Code coverage of files in pull request scope (71.9% → 72.5%)

Files	Coverage	+/-
book.go	73.2%	+0.1%
operator.go	77.6%	0.0%
option.go	65.1%	+2.3%
path.go	75.0%	+4.7%
scope.go	75.0%	+75.0%
testutil/port.go	0.0%	0.0%

---

Reported by octocov

[k1LoW]

Thank you @k2tzumi !

ref: https://x.com/katzchum/status/1719324320017854602?s=20