Improve StackTraceFormatter

[Nevay]

Resolves some issues with the stacktrace formatter.

• Fix "... n more" to fold only identical frames, currently we might lose information due to folding on first seen frame instead of folding last n identical frames as described by Java ("These lines indicate that the remainder of the stack trace for this exception matches the indicated number of frames from the bottom of the stack trace of the exception that was caused by this exception (the "enclosing" exception).")
• Fix exception class names not being converted to dotted format
• Fix functions being shown as main
• Fix out-of-memory on circular exception

Example output to highlight some of the differences:

# new
Abc.Def.Test: bar
	at Abc.Def.Test.create(Test.php:10)
	at Abc.Def.run(example.php:8)
	at {main}(example.php:12)
Caused by: Abc.Def.Test: foo
	at Abc.Def.Test.create(Test.php:10)
	at Abc.Def.run(example.php:7)
	... 1 more

# old
Abc\Def\Test: bar
 at Abc.Def.Test.create(Test.php:10)
 at main(example.php:8)
 at main(example.php:12)
Caused by: Abc\Def\Test: foo
 ... 3 more

Additionally this changes the output format:

• indent is now 1 tab instead of 1 space
• empty messages are no longer displayed (no : ) - what is the desired behavior? Java prints nothing for null and : for empty.
• main is now displayed as {main} instead of main to avoid confusion with a function named main (curly brackets for consistency with {closure})

Currently it's not possible to run the tests with PHPUnit (<directory suffix=".phpt">./tests/Unit</directory>) due to PHPUnit loading the scripts using require, which changes the stacktrace. run-tests.php can be used instead (not executed automatically for now in hopes that this will be resolved).

[codecov]

Codecov Report

Merging #697 (a245180) into main (e728c53) will decrease coverage by 0.78%.
The diff coverage is 1.51%.

@@             Coverage Diff              @@
##               main     #697      +/-   ##
============================================
- Coverage     83.82%   83.04%   -0.79%     
- Complexity     1233     1234       +1     
============================================
  Files           138      138              
  Lines          2980     3008      +28     
============================================
  Hits           2498     2498              
- Misses          482      510      +28     

Flag	Coverage Δ
7.4	83.03% <1.51%> (-0.79%)	⬇️
8.0	83.09% <1.51%> (-0.79%)	⬇️
8.1	83.09% <1.51%> (-0.79%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
src/SDK/Common/Exception/StackTraceFormatter.php	0.00% <0.00%> (ø)
src/SDK/Trace/Span.php	93.69% <100.00%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update e728c53...a245180. Read the comment docs.