fix: ensure docker runtimes support dockerignore, empty build args and ignore other entrypoint files

[davemooreuws]

• Stops the CLI from breaking when no args are defined
• Allows .dockerignore to be used for default runtimes
• Allows a custom runtime to define a dockerignore by "[dockerfile]".dockerignore
• Adds other entrypoint files to dockerignore

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 17.94872% with 32 lines in your changes are missing coverage. Please review.

Project coverage is 1.42%. Comparing base (8e4861d) to head (39a196e).

Files	Patch %	Lines
pkg/project/runtime/runtime.go	20.58%	24 Missing and 3 partials :warning:
pkg/project/project.go	0.00%	5 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #703 +/- ## ======================================== + Coverage 1.33% 1.42% +0.08% ======================================== Files 73 73 Lines 7342 7376 +34 ======================================== + Hits 98 105 +7 - Misses 7239 7263 +24 - Partials 5 8 +3 ``` | [Flag](https://app.codecov.io/gh/nitrictech/cli/pull/703/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=nitrictech) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/nitrictech/cli/pull/703/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=nitrictech) | `1.42% <17.94%> (+0.08%)` | :arrow_up: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=nitrictech#carryforward-flags-in-the-pull-request-comment) to find out more.

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[nitric-bot]

:tada: This PR is included in version 1.37.3 :tada:

The release is available on GitHub release

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