cgen: fix call_expr in branches and left_expr of call_expr with or_block(fix #20044)

[shove70]

1. Fixed Builder error when calling method on or block result in if expression #20044
2. Add tests.

fn baz(str string) !string {
	return str
}

foo := '/bar'
bar := if foo.contains('foo') {
	foo.all_after('foo')
} else {
	baz(foo) or { panic('panic') }.trim_left('/')
}

assert bar == 'bar'
println(bar)

outputs:

bar