Update introductory graphic for Reading list panel

[GeetaSarvadnya]

Description

Reading list graphics is inherited from chrome

Actual result:

Expected result:

See: #24927 (comment)

Reproduces how often:

Easy

Brave version (brave://version info)

Brave	1.44.64 Chromium: 105.0.5195.37 (Official Build) nightly (64-bit)
Revision	5f67e9f258cc28ab970e57572290edf1863ee3c5-refs/branch-heads/5195@{#621}
OS	Windows 10 Version 21H2 (Build 19044.1889)

Version/Channel Information:

• Can you reproduce this issue with the current release? NA
• Can you reproduce this issue with the beta channel? NA
• Can you reproduce this issue with the nightly channel? Yes

Other Additional Information:

• Does the issue resolve itself when disabling Brave Shields? NA
• Does the issue resolve itself when disabling Brave Rewards? NA
• Is the issue reproducible on the latest version of Chrome? NA

Miscellaneous Information:

cc: @brave/qa-team @rebron @bradleyrichter

[aguscruiz]

Already have a design for this, link here: https://www.figma.com/file/xOdKFSr3P5AXSAbP2r8ung/Sidebar-Desktop?node-id=3862%3A70675

[stephendonner]

Verified PASSED using

Brave	1.51.76 Chromium: 112.0.5615.49 (Official Build) beta (x86_64)
Revision	bd2a7bcb881c11e8cfe3078709382934e3916914-refs/branch-heads/5615@{#936}
OS	macOS Version 13.4 (Build 22F5027f)

Post-fix

Figma spec	Light	Dark

Previous

Light	Dark

[stephendonner]

Verified PASSED using

Brave	1.51.87 Chromium: 112.0.5615.49 (Official Build) beta (64-bit)
Revision	bd2a7bcb881c11e8cfe3078709382934e3916914-refs/branch-heads/5615@{#936}
OS	Windows 10 Version 22H2 (Build 19045.2846)

Dark	Light