Disassembler for inspecting compiled Risor code

[myzie]

Adds a disassembler package and Risor CLI command to inspect compiled Risor code.

For example:

risor dis -c "1 + 2"
+--------+------------+----------+------+
| OFFSET |   OPCODE   | OPERANDS | INFO |
+--------+------------+----------+------+
|      0 | LOAD_CONST |        0 | 1    |
|      2 | LOAD_CONST |        1 | 2    |
|      4 | BINARY_OP  |        1 | +    |
+--------+------------+----------+------+

Other supporting changes:

• Minor reorganization of cmd/risor package to clean things up
• Make opcode integers fixed rather than using iota
• make tidy

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 29.83294% with 294 lines in your changes are missing coverage. Please review.

Project coverage is 31.44%. Comparing base (a897b5c) to head (29f05fc).

Files	Patch %	Lines
cmd/risor/util.go	0.86%	112 Missing and 2 partials :warning:
dis/dis.go	55.85%	45 Missing and 4 partials :warning:
op/op.go	9.80%	46 Missing :warning:
cmd/risor/options.go	50.87%	18 Missing and 10 partials :warning:
cmd/risor/root.go	18.51%	22 Missing :warning:
cmd/risor/dis.go	41.66%	16 Missing and 5 partials :warning:
cmd/risor/version.go	38.09%	13 Missing :warning:
cmd/risor/main.go	0.00%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #202 +/- ## ========================================== - Coverage 31.52% 31.44% -0.09% ========================================== Files 113 121 +8 Lines 14461 15103 +642 ========================================== + Hits 4559 4749 +190 - Misses 9331 9763 +432 - Partials 571 591 +20 ```

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