fix: support for parsing escaped #line tags

[cmaglie]

Previously #line tags were not correctly parsed if they contained escaped chars like \"

$ cat /tmp/test.cpp
# 1 "/home/megabug/Workspace/arduino-cli/internal/integrationtest/testdata/PathWith\"Quotes/Sketch/Sketch.ino"
void setup() {
  foo();
}
void loop() {}
void foo() {}
$ ./ctags -u --language-force=c++ -f - --c++-kinds=svpf --fields=KSTtzns --line-directives /tmp/test.cpp
$

after this patch the line directives are parsed correctly:

$ cat /tmp/test.cpp
# 1 "/home/megabug/Workspace/arduino-cli/internal/integrationtest/testdata/PathWith\"Quotes/Sketch/Sketch.ino"
void setup() {
  foo();
}
void loop() {}
void foo() {}
$ ./ctags -u --language-force=c++ -f - --c++-kinds=svpf --fields=KSTtzns --line-directives /tmp/test.cpp
setup	/home/megabug/Workspace/arduino-cli/internal/integrationtest/testdata/PathWith"Quotes/Sketch/Sketch.ino	/^void setup() {$/;"	kind:function	line:1	signature:()	returntype:void
loop	/home/megabug/Workspace/arduino-cli/internal/integrationtest/testdata/PathWith"Quotes/Sketch/Sketch.ino	/^void loop() {}$/;"	kind:function	line:4	signature:()	returntype:void
foo	/home/megabug/Workspace/arduino-cli/internal/integrationtest/testdata/PathWith"Quotes/Sketch/Sketch.ino	/^void foo() {}$/;"	kind:function	line:5	signature:()	returntype:void
$