[FEATURE] Create a triangle header image widget

[manav2modi]

Description

Creating a triangle header image widget so that it can be reused in other places.
Example - Single images on the bottomsheet for the place description

Fixes #488

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[mihail-varbanov]

@manav2modi,

1. I guess you want this merged in support/v1.7, not in develop? That's why I closed your pull request and created & merged a new one pointing to the right target branch.

2. Please pay attention to the commits that I added in your work branch. I am getting tired of rejecting your PRs for the same reasons so many times.

3. Hint: when you add your commits in your work branch, if you add the number of the GIT issue inside the commit message text, GIT links this commit to the issue that it is related to and lists it in the issue activity page. For illustration, you could see how my commits are listed in [FEATURE] Create a triangle header image widget #488 page. This makes easier to observe what work had been done on given GIT issue.