Add test for issue #3170 curly brace priority limit

Test verifies:
- Priority 1200 operators in curly braces error correctly
- Priority 1199 operators in curly braces work
- Parenthesized priority 1200 operators work

J.J.'s Robot

Author: jjtolton

tests/scryer/cli/issues/issue_3170_curly_operator.md

@@ -0,0 +1,40 @@
+# Issue #3170: Enforce priority 1199 limit in curly braces
+
+## Test that priority 1200 operator in curly braces throws syntax error
+
+```trycmd
+$ scryer-prolog -f --no-add-history
+?- use_module(library(charsio)).
+   true.
+?- op(1200,xfx,~>).
+   true.
+?- read_from_chars("{a~>b}.",T).
+   error(syntax_error(incomplete_reduction),read_term_from_chars/3:0).
+?- halt.
+```
+
+## Test that priority 1199 operator in curly braces works
+
+```trycmd
+$ scryer-prolog -f --no-add-history
+?- use_module(library(charsio)).
+   true.
+?- op(1199,xfx,~>).
+   true.
+?- read_from_chars("{a~>b}.",T).
+   T = {a~>b}.
+?- halt.
+```
+
+## Test that parenthesized priority 1200 operator in curly braces works
+
+```trycmd
+$ scryer-prolog -f --no-add-history
+?- use_module(library(charsio)).
+   true.
+?- op(1200,xfx,~>).
+   true.
+?- read_from_chars("{(a~>b)}.",T).
+   T = {a~>b}.
+?- halt.
+```