Implemented function calls from lambdas, stored variables and expressions

[Luna-Klatzer]

What type of change does this PR perform?

• Info or documentation change (Non-breaking change that updates repo info files (e.g. README.md, CONTRIBUTING.md, etc.) or online documentation)
• Website (Change that changes the design or functionality of the websites or docs)
• Development or internal changes (These changes do not add new features or fix bugs, but update the code in other ways)
• Bug fix (Non-breaking change which fixes an issue)
• New feature (Non-breaking change which adds functionality)
• Breaking change (Major bug fix or feature that would cause existing functionality not to work as expected.)
• Requires a documentation update, as it changes language or compiler behaviour

Summary

Implemented function calls from lambdas, stored variables and expressions so that any expression that returns a function can be called.

Closes #674

Detailed Changelog

Not present for website/docs changes

Added

• Support for calling lambdas and functions stored in variables or expressions. (#674)

Fixed

• CLI command run not properly reporting internal or unexpected errors, as they were already prettified in the
  internally called up command compile.

Does this PR create new warnings?

None.

Linked issues or PRs

• [Feature] Implement function calls from function references (variable-bound functions) #674