Back End Grammar support for Web Server (separate from PR #855)

**Is your feature request related to a problem? Please describe.**
It isn't really a problem, it is more a detriment to performance of the Server.

**Describe the solution you'd like**
Currently, you pass "grammar" as a function in your call, and then that grammar is parsed every single time for every single call you make to the web server.

I would like to pass the grammar to the webserver upon start up, and then use it for all calls thereafter.

**Describe alternatives you've considered**
The current version works, but every call looks like this:

```
from_string grammar:
root ::= answer
answer ::= [{] ws ]
ws ::= ws_10
string ::= ["] string_7 ["]
etc etc.

"POST /v1/completions HTTP/1.1" 200 OK
```

**Additional context**
There is likely a way for someone with higher level python skills than me to manipulate the code on the back end through a source build - I just figure, if I want it, I suspect others will want it at some point to....since grammar is quite frankly an astonishingly good addition.

Thanks.