Deprecate NoRuntimeChecks, add dedicated API

[nickclark2016]

What does this PR do?

Deprecates the NoRuntimeChecks flag. Adds a new API for `runtimechecks with the following fields:

• Default (uses exporter defaults)
• Off (performs no checks, maps to "Default" in IDE, maps to NoRuntimeChecks flag behavior)
• StackFrame (stack frame checks)
• UninitializedVariables (uninit variable checks)
• FastChecks (all fast checks)

How does this PR change Premake's behavior?

No breaking changes

Anything else we should know?

Prep for 5.0

Did you check all the boxes?

• Focus on a single fix or feature; remove any unrelated formatting or code changes
• Add unit tests showing fix or feature works; all tests pass
• Mention any related issues (put closes #XXXX in comment to auto-close issue when PR is merged)
• Follow our coding conventions
• Minimize the number of commits
• Align documentation to your changes

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[redorav]

Not quite sure I understand this comment:

Off (performs no checks, maps to "Default" in IDE, maps to NoRuntimeChecks flag behavior)

Particularly the "maps to Default" and "uses exporter defaults" bits, the comments in the docs do sound sensible but contradict the comment, am I reading these wrong?

[nickclark2016]

Not quite sure I understand this comment:

Off (performs no checks, maps to "Default" in IDE, maps to NoRuntimeChecks flag behavior)

Particularly the "maps to Default" and "uses exporter defaults" bits, the comments in the docs do sound sensible but contradict the comment, am I reading these wrong?

Yeah, I'm not sure what the best way to word this is. Basically, if we want to be "Default" in how Premake defines the default (aka don't emit a value and just let the exporter determine), we need to leave it empty. However, there is an explicit "Default" value in VS that actually maps better to "Off" (Microsoft sucks at naming). Would gladly take any wording suggestions here.