feat: Generate SBOM for a single file

[nightlark]

Enable users to generate an SBOM for a single file, without having to create a config file. If a file name ends with .json it is treated as a specimen config file, rather than generating a single-file SBOM for the JSON file. To override this behavior, several prefixes can be prepended to the file path so the argument to Surfactant will be in the form prefix:filepath -- e.g. file:abc.json.

The prefixes recognized are:

• file to force Surfactant to generate an SBOM from the single file given after the prefix. Likely only needed to generate a single file SBOM for a JSON file or a file whose name starts with one of the special prefixes as part of the file name, both of which should be rare. e.g. file:config:abc.xyz would generate a single file SBOM for a file with the (odd) name config:abc.xyz
• config to force Surfactant to treat the given file path as a Surfactant specimen config file. This should never be needed, unless a user decides to omit a .json file extension for their Surfactant specimen config file names.
• dir to force Surfactant to treat the given file path as a specific directory to generate an SBOM for, with "implied" specimen config file settings (summarized below). This should only be needed if a directory has one of these special prefixes at the start of its name, which is very rare. e.g. dir:config:mydirectory would generate an SBOM over the contents in a directory named config:mydirectory.

For generating a single file or single directory SBOM some assumptions are made for parameters that a specimen config file would usually contain:

• extractPaths: the path given as an argument to Surfactant
• installPrefix: either the directory given as the argument to Surfactant, or the parent directory if the path given to Surfactant is for a single file SBOM; a relative path to a file will result in this being a relative path while an absolute path will result in this being the absolute path, which gives some control over the install paths present in the resulting SBOM

Resolves #126