Add text output format

[michaelkedar]

Adds --format text option for outputting scan results, per #85

Outputs a numbered list of each vulnerability for each package, including all aliases.

Sample output format:

path/to/Cargo.lock:
  regex@1.3.1 is affected by the following vulnerabilities:
      1. https://osv.dev/GHSA-m5pq-gvj9-9vr8 - Rust's regex crate vulnerable to regular expression denial of service
         https://osv.dev/RUSTSEC-2022-0013   - Regexes with large repetitions on empty sub-expressions take a very lo...

path/to/go.mod:
  github.com/gogo/protobuf@1.3.1 is affected by the following vulnerabilities:
      1. https://osv.dev/GHSA-c3h9-896r-86jm - Improper Input Validation in GoGo Protobuf
         https://osv.dev/GO-2021-0053        - Due to improper bounds checking, maliciously crafted input to generate...

path/to/requirements.txt:
  jinja2@2.0 is affected by the following vulnerabilities:
      1. https://osv.dev/GHSA-462w-v97r-4m45 - High severity vulnerability that affects Jinja2
         https://osv.dev/PYSEC-2019-217      - In Pallets Jinja before 2.10.1, str.format_map allows a sandbox escape.
      2. https://osv.dev/GHSA-8r7q-cvjq-x353 - Incorrect Privilege Assignment in Jinja2
         https://osv.dev/PYSEC-2014-8        - The default configuration for bccache.FileSystemBytecodeCache in Jinja...
      3. https://osv.dev/GHSA-g3rq-g295-4j3m - Regular Expression Denial of Service (ReDoS) in Jinja2
         https://osv.dev/PYSEC-2021-66       - This affects the package jinja2 from 0.0.0 and before 2.11.3. The ReDo...
      4. https://osv.dev/GHSA-hj2j-77xm-mc5v - High severity vulnerability that affects Jinja2
         https://osv.dev/PYSEC-2019-220      - In Pallets Jinja before 2.8.1, str.format allows a sandbox escape.
      5. https://osv.dev/PYSEC-2014-82       - FileSystemBytecodeCache in Jinja2 2.7.2 does not properly create tempo...

(It's also in colour in terminals)

[G-Rath]

Looks good! personally, I don't think I'm a big fan of the numbering as I don't know if it adds much value - I'd just have each item indented two spaces in (which'd also free up a couple of extra chars as you're currently doing four); but that's just my two cents :)

[michaelkedar]

After some offline discussion, there was a decision to be more selective/deliberate on whether we should be adding more supported output formats.

I'm going to close this for now, though it might be revisited if we identify a need or demand for a text format.