feat: parse lockfile information and combine into chart info #285

[ominiet]

Parse Chart lockfile information

This PR adds a new function parseChartLockFile in the style of the existing parseChartFile function as mentioned in Issue #285

Changes

1. Add new function parseChartLockFile that accepts chartInfo from parseChartFile and returns a ChartRequirements struct that may be modified by the information found in Chart.lock or requirements.lock

   1. If no lockfile is found, it will return the ChartRequirements unmodified
   2. If lockfile is found, it will validate the entries in the chart's dependencies list match on index, chart name, and version constraint and, if so, bring exact versions and repository URLs into the ChartRequirements info struct.

2. Move dependency list sorting to ParseChartInformation

   1. This may be necessary because Chart.lock relies on index ordering of the existing dependencies list. Otherwise, the only identifier is chart name, which may be repeated in a dependency list

Tests

I added one new test into chart_info_test.go, which checks for the final output of ParseChartInformation with aliases, version range constraints and repeated dependencies