feat: update logos and map grayscale to monochrome for 5.1 rebrand

[fjabbary]

https://paypal.atlassian.net/browse/DTCRCMERC-4392

Description

• Replace all PayPal and PayPal Credit logo assets (primary, alternative, inline) with updated 5.1 branding
  across all color variants (black, white, monochrome) at 1x, 2x, and 3x resolutions
  • Map .grayscale color option to monochrome assets — the 5.1 branding drops the grayscale variant; existing
    integrations using .grayscale will now render identically to .monochrome

Screenshots

Pay Later

PayPal Credit

Testing instructions

• Fetch the branch and run the app in xcode. Use client ID below: AXwqp8zar6XYxrzjUGyMLiCUt4cUAgEbLMZZxKMa51We6m_lRtccWYVyl0Zf8kTvq06aaogesJwpSQeN
• Verify primary/alternative/inline logos render correctly in simulator across all color options (Black,
  White, Monochrome, Grayscale)
• Verify Grayscale and Monochrome render identically
• Verify PayPal Credit logo variants render correctly
• Verify None logo type still renders bold text correctly

[yeul]

@fjabbary I noticed the inline logos look a little bit compressed, like they've been squeezed. Can we take a look into that? Can we also take a look into updating the "Learn more" link to the updated blue (#0065F2) for non-monochrome/grayscale/white variants?

[fjabbary]

@fjabbary I noticed the inline logos look a little bit compressed, like they've been squeezed. Can we take a look into that? Can we also take a look into updating the "Learn more" link to the updated blue (#0065F2) for non-monochrome/grayscale/white variants?

@yeul Link color updated to #0065F2 (not reflected in screen shots) and all logos including the inline ones replaced with the figma file provided (it was previously incorrect scale of 0.5x, 1x, 1.5x, now is 1x, 2x, 3x).