Add support for conditional dependencies

[johbo]

It would be great to have support for the attribute condition in the dependencies section. Then the value of the condition could be rendered into the output.

The below example shows a case from a chart which I am currently working on, it's allowing to bundle the database for ease of use. Showing that this is a conditional dependencies and showing the value of the condition would be of value to users who study the file README.md.

Example:

dependencies:
  - name: "common"
    repository: "https://charts.bitnami.com/bitnami"
    version: "^2.2.2"
  - name: "postgresql"
    repository: "https://charts.bitnami.com/bitnami"
    version: "^12.2.1"
    condition: "postgresql.bundled"

Using {{ . | toPrettyJson }} I found that only the following data is available for the template:

  "Dependencies": [
    {
      "Name": "common",
      "Version": "^2.2.2",
      "Repository": "https://charts.bitnami.com/bitnami",
      "Alias": ""
    },
    {
      "Name": "postgresql",
      "Version": "^12.2.1",
      "Repository": "https://charts.bitnami.com/bitnami",
      "Alias": ""
    }
  ],

Staying consistent with the naming scheme, the new attribute should be called Condition.

The new default templates could render this as follows:

| Repository | Name | Version | Condition |
|------------|------|---------|-----------|
| https://charts.bitnami.com/bitnami | common | ^2.2.2 | |
| https://charts.bitnami.com/bitnami | postgresql | ^12.2.1 | `postgresql.bundled` |