allow env vars for all exec units from config

[jhsinger-klotho]

• Does any part of it require special attention?
• Does it relate to or fix any issue? closes #119

allows env vars to be attached to an execution unit through config in a standard way across types.

Changes to pro are in a different pr

Standard checks

• Unit tests: Any special considerations? Added unit tests for exec unit plugin
• Docs: Do we need to update any docs, internal or public? need to add docs
• Backwards compatibility: Will this break existing apps? If so, what would be the extra work required to keep them working? yes, new feature and wont conflict with pulumi passthrough

[github-actions]

Package	Line Rate	Health
github.com/klothoplatform/klotho/pkg/analytics	2%	❌
github.com/klothoplatform/klotho/pkg/annotation	23%	❌
github.com/klothoplatform/klotho/pkg/cli	4%	❌
github.com/klothoplatform/klotho/pkg/core	20%	❌
github.com/klothoplatform/klotho/pkg/env_var	82%	✔
github.com/klothoplatform/klotho/pkg/exec_unit	54%	➖
github.com/klothoplatform/klotho/pkg/infra/kubernetes	59%	➖
github.com/klothoplatform/klotho/pkg/infra/kubernetes/helm	39%	❌
github.com/klothoplatform/klotho/pkg/input	63%	➖
github.com/klothoplatform/klotho/pkg/lang	37%	❌
github.com/klothoplatform/klotho/pkg/lang/dockerfile	0%	❌
github.com/klothoplatform/klotho/pkg/lang/golang	9%	❌
github.com/klothoplatform/klotho/pkg/lang/javascript	47%	❌
github.com/klothoplatform/klotho/pkg/lang/python	60%	➖
github.com/klothoplatform/klotho/pkg/lang/yaml	0%	❌
github.com/klothoplatform/klotho/pkg/logging	7%	❌
github.com/klothoplatform/klotho/pkg/multierr	95%	✔
github.com/klothoplatform/klotho/pkg/provider/aws	59%	➖
github.com/klothoplatform/klotho/pkg/runtime	75%	✔
github.com/klothoplatform/klotho/pkg/static_unit	32%	❌
github.com/klothoplatform/klotho/pkg/validation	73%	➖
github.com/klothoplatform/klotho/pkg/yaml_util	79%	✔
Summary	40% (3722 / 9373)	❌