[FEATURE] [FRONTEND] H5P player(s) should show loading feedback during initialization

[0xMurage]

Describe the user story:

When the H5P player is loading the content to play, a progress loader should be shown until everything is loaded successfully or an error is encountered. Meaningful feedback should be shown to the user if an error is experienced.

Tasks (where applicable)

• Implement H5P player initialization loader
• Replace the above loading feedback once the H5P player emits the first attempted xAPI event statement or when an error is encountered

Tests (where applicable)

• T.B.D

Acceptance Criteria

• H5P player initialization feedback is shown until content is loaded successfully or an error is encountered
• H5P initialization error feedback is shown to the user if an error is encountered

Screenshots where applicable