Introduce --parser runtime flag

Introduce runtime flag for specifying the parser,

```
ruby --parser=prism
```

also update the description:

```
$ ruby --parser=prism --version
ruby 3.3.0dev (2023-12-08T04:47:14Z add-parser-runtime.. 0616384c9f) +PRISM [x86_64-darwin23]
```

[Bug #20044]

1 files changed, 2 insertions, 0 deletions

diff --git a/iseq.h b/iseq.h
index 210c79906d..d71f37ca13 100644
--- a/iseq.h
+++ b/iseq.h
@@ -13,6 +13,7 @@
 #include "internal/gc.h"
 #include "shape.h"
 #include "vm_core.h"
+#include "prism_compile.h"
 
 RUBY_EXTERN const int ruby_api_version[];
 #define ISEQ_MAJOR_VERSION ((unsigned int)ruby_api_version[0])
@@ -173,6 +174,7 @@ void rb_iseq_init_trace(rb_iseq_t *iseq);
 int rb_iseq_add_local_tracepoint_recursively(const rb_iseq_t *iseq, rb_event_flag_t turnon_events, VALUE tpval, unsigned int target_line, bool target_bmethod);
 int rb_iseq_remove_local_tracepoint_recursively(const rb_iseq_t *iseq, VALUE tpval);
 const rb_iseq_t *rb_iseq_load_iseq(VALUE fname);
+rb_iseq_t * rb_iseq_new_main_prism(pm_string_t *input, pm_options_t *options, VALUE path);
 
 #if VM_INSN_INFO_TABLE_IMPL == 2
 unsigned int *rb_iseq_insns_info_decode_positions(const struct rb_iseq_constant_body *body);