ui,cli: add -j json output

[nmanthey]

When running weggli on multiple projects, or with multiple queries on project, leaving traces of the activities on disk helps to revisit findings later on again. Hence, this change extends weggli to keep track of its activities by storing a JSON file with the invocation, as well as the findings and a brief summary.

Testing Done

I executed weggli on a simple example input file with this feature enabled:

rm -f output.json && cargo build --release && ./target/release/weggli --json output.json 'memcpy($buf,_,_);' test_file.c && cat output.json

Release build:

warning: `/home/ANT.AMAZON.COM/nmanthey/projects/weggli/.cargo/config` is deprecated in favor of `config.toml`
note: if you need to support cargo 1.38 or earlier, you can symlink `config` to `config.toml`
    Finished `release` profile [optimized] target(s) in 0.27s

Run output :

int main() {
    char buf[100];
    memcpy(buf, "hello", 5);
    return 0;

test_file.c:10
void vulnerable_function() {
    char stack_buffer[256];
    memcpy(stack_buffer, "data", 4);
}

JSON output:

{
  "matches": [
    {
      "path": "test_file.c",
      "line": 4,
      "lines": {
        "4": "int main() {",
        "6": "    memcpy(buf, \"hello\", 5);"
      }
    },
    {
      "path": "test_file.c",
      "line": 10,
      "lines": {
        "10": "void vulnerable_function() {",
        "12": "    memcpy(stack_buffer, \"data\", 4);"
      }
    }
  ],
  "summary": {
    "matched_patterns": 2
  },
  "parameters": {
    "pattern": [
      "memcpy($buf,_,_);"
    ],
    "path": "test_file.c",
    "before": 5,
    "after": 5,
    "extensions": [
      "c",
      "h"
    ],
    "regexes": [],
    "limit": false,
    "cpp": false,
    "unique": false,
    "include": [],
    "exclude": []
  }
}

Actual file:

#include <stdio.h>
#include <string.h>

int main() {
    char buf[100];
    memcpy(buf, "hello", 5);
    return 0;
}

void vulnerable_function() {
    char stack_buffer[256];
    memcpy(stack_buffer, "data", 4);
}