Write analysis JSON to provided file, format

[ryangreenberg]

hakana analyze only respects --output if the filename is "checkpoint_results.json". This PR changes the command to writes the output to any given path and adds --json-format to specify the desired output format.

The options allowed for --json-format are:

• checkpoint: the current default
• hh_client: format that can be interpreted in the same way as error messages from Meta's Hack typechecker
• full: the issue and description with all information from the HPos

After adding hh_client and documenting the meaning of start and end, I opted to add full because it's easier to work with. Details inline; happy to drop hh_client entirely. Can also rename full if desired.

[ryangreenberg]

Explaining this code prompted me to switch to creating FullEntry instead.

I find the meaning of start and end somewhat confusing: they are offsets starting from the offset of the given line. This is equivalent to start_column, end_column when the error is contained to a single line but different for multi-line errors. This is a little annoying to work with programmatically (start_offset and end_offset from the start of the file would be easier).

For this input:

function example(): void {
	takes_int(
		"the quick brown fox jumped over the lazy dog".
		"the quick brown fox jumped over the lazy dog".
		"the quick brown fox jumped over the lazy dog",
	);
}

function takes_int(int $i): void {}

hh_client produces the following output (via hh_client --json | jq .):

{
  "descr": "Invalid argument",
  "path": "/mnt/dev1725/example.hack",
  "line": 3,
  "start": 3,
  "end": 148,
  "code": 4110
}

This shows up as an error at:

function example(): void {
	takes_int(
		"the quick brown fox jumped over the lazy dog".
		^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
		"the quick brown fox jumped over the lazy dog".
		^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
		"the quick brown fox jumped over the lazy dog",
		^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
	);
}

In the given example, the start of line 3 corresponds to character 38. +3 chars gives you the opening " and +148 chars gives you the closing " 2 lines later.