improve semantic manifest error message

[Klimmy]

resolves #9849

Problem

Improves this error message to provide more details as to what is wrong with the Semantic Manifest.

Solution

This PR moved the raising of an error to the validate() method and made it return None instead of bool.
From what I checked, this behavior aligns with other validations in the project (example_1, example_2, example_3).

Before the fix:

Encountered an error:
Parsing Error
  Semantic Manifest validation failed.

After the fix:

Encountered an error:
Parsing Error
  Semantic Manifest validation failed due to the following:
  - Invalid name `metric_time` - this name is reserved by MetricFlow. Reason: Used as the query input for creating time series metrics from measures with different time dimension names.
  - The semantic model orders contains dimensions, but it does not define a primary entity. Either add an entity with type PRIMARY or set a value for the primary_entity key.

Checklist

• I have read the contributing guide and understand what's expected of me
• I have run this code in development and it appears to resolve the stated issue
• This PR includes tests, or tests are not required/relevant for this PR
• This PR has no interface changes (e.g. macros, cli, logs, json artifacts, config files, adapter interface, etc)
• This PR includes type annotations for new and modified functions

[github-actions]

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