Add Column Pinning and support deleting & changing visibility of custom views

[Siddhantsingh1230]

Description

This PR introduces the ability to pin columns in the next-pms app for better user experience and control over table layouts. It also adds support for deleting custom views and toggling their visibility from private to public.

The following changes have been completed as part of this PR:

• Updated approval message to: "Timesheet approval or rejection has been queued for processing. Please do not make any changes to it. You may continue with other tasks."
• Fields in the Project detail page now support values up to 2 decimal places
• Fixed leave allocation styling in Resource Timeline view for dark mode
• Add fallback icon to viewloader in sidebar

Relevant Technical Choices

• Add Pinned Columns in PMS View Settings doctype to store i.e Array of strings

Testing Instructions

• Go to NPMS
• Try Pinning columns in Project and Task page
• Try Creating views , make private views public or delete them

Additional Information:

Public views cannot be deleted or changed back to private from NPMS.

Screenshot/Screencast

Resource Timeline:

Project Detail

Fallback Icon in ViewLoader

Column.pinning.webm

Checklist

• I have carefully reviewed the code before submitting it for review.
• This code is adequately covered by unit tests to validate its functionality.
• I have conducted thorough testing to ensure it functions as intended.
• A member of the QA team has reviewed and tested this PR (To be checked by QA or code reviewer)

Addresses: https://github.com/rtCamp/erp-rtcamp/issues/2394