fix(FEC-14047): playkit-js-providers - add aspectRatio to media metadata

[SivanA-Kaltura]

Description of the Changes

Changes since previous PR:

• Rename to aspectRatio, which is the standard name
• Divide width by height and not vice versa
• Remove the default value
• Fix unit tests

Why we don't want to set a default value:

• Default value was set when context / height / width were not set. This happened when fetching the partial sources data for playlist.
• Meaning, the partial source of an entry in playlist always had an INITIAL value of aspectRatio = 1.78
• When loadMedia was called, this code was called again, with context this time, and it returned a source with the CORRECT value of aspectRatio
• The player would then try to merge the two sources objects (partial and full), but because the initial aspectRatio was already set - the correct value did not override the initial value, since it would only override values which are not yet set.
• This caused the entry aspectRatio to have an incorrect value.

Resolves FEC-14047