NOTCH1 and esophageal squamous cell carcinoma: Findings that TME in ESCC is enriched in Treg and TEX but deficient in TEFF and TMEM; revelation of the activation of CAFs in the development of ESCC; significant correlation between the level of gene expression in the mucosal immune‐like program and the survival time of patients with ESCC and the effect of somatic mutations (e.g., TP53 and NOTCH1)